set svn:eol-style

1 files changed, 2351 insertions, 2351 deletions

diff --git a/Lib/argparse.py b/Lib/argparse.py
index e91bb7a..cde1fe9 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1,2351 +1,2351 @@
-# Copyright 2006-2009 Steven J. Bethard <steven.bethard@gmail.com>.

-#

-# Licensed under the Apache License, Version 2.0 (the "License"); you may not

-# use this file except in compliance with the License. You may obtain a copy

-# of the License at

-#

-#     http://www.apache.org/licenses/LICENSE-2.0

-#

-# Unless required by applicable law or agreed to in writing, software

-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT

-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the

-# License for the specific language governing permissions and limitations

-# under the License.

-

-"""Command-line parsing library

-

-This module is an optparse-inspired command-line parsing library that:

-

-    - handles both optional and positional arguments

-    - produces highly informative usage messages

-    - supports parsers that dispatch to sub-parsers

-

-The following is a simple usage example that sums integers from the

-command-line and writes the result to a file::

-

-    parser = argparse.ArgumentParser(

-        description='sum the integers at the command line')

-    parser.add_argument(

-        'integers', metavar='int', nargs='+', type=int,

-        help='an integer to be summed')

-    parser.add_argument(

-        '--log', default=sys.stdout, type=argparse.FileType('w'),

-        help='the file where the sum should be written')

-    args = parser.parse_args()

-    args.log.write('%s' % sum(args.integers))

-    args.log.close()

-

-The module contains the following public classes:

-

-    - ArgumentParser -- The main entry point for command-line parsing. As the

-        example above shows, the add_argument() method is used to populate

-        the parser with actions for optional and positional arguments. Then

-        the parse_args() method is invoked to convert the args at the

-        command-line into an object with attributes.

-

-    - ArgumentError -- The exception raised by ArgumentParser objects when

-        there are errors with the parser's actions. Errors raised while

-        parsing the command-line are caught by ArgumentParser and emitted

-        as command-line messages.

-

-    - FileType -- A factory for defining types of files to be created. As the

-        example above shows, instances of FileType are typically passed as

-        the type= argument of add_argument() calls.

-

-    - Action -- The base class for parser actions. Typically actions are

-        selected by passing strings like 'store_true' or 'append_const' to

-        the action= argument of add_argument(). However, for greater

-        customization of ArgumentParser actions, subclasses of Action may

-        be defined and passed as the action= argument.

-

-    - HelpFormatter, RawDescriptionHelpFormatter, RawTextHelpFormatter,

-        ArgumentDefaultsHelpFormatter -- Formatter classes which

-        may be passed as the formatter_class= argument to the

-        ArgumentParser constructor. HelpFormatter is the default,

-        RawDescriptionHelpFormatter and RawTextHelpFormatter tell the parser

-        not to change the formatting for help text, and

-        ArgumentDefaultsHelpFormatter adds information about argument defaults

-        to the help.

-

-All other classes in this module are considered implementation details.

-(Also note that HelpFormatter and RawDescriptionHelpFormatter are only

-considered public as object names -- the API of the formatter objects is

-still considered an implementation detail.)

-"""

-

-__version__ = '1.1'

-__all__ = [

-    'ArgumentParser',

-    'ArgumentError',

-    'Namespace',

-    'Action',

-    'FileType',

-    'HelpFormatter',

-    'RawDescriptionHelpFormatter',

-    'RawTextHelpFormatter',

-    'ArgumentDefaultsHelpFormatter',

-]

-

-

-import copy as _copy

-import os as _os

-import re as _re

-import sys as _sys

-import textwrap as _textwrap

-

-from gettext import gettext as _

-

-try:

-    _set = set

-except NameError:

-    from sets import Set as _set

-

-try:

-    _basestring = basestring

-except NameError:

-    _basestring = str

-

-try:

-    _sorted = sorted

-except NameError:

-

-    def _sorted(iterable, reverse=False):

-        result = list(iterable)

-        result.sort()

-        if reverse:

-            result.reverse()

-        return result

-

-

-def _callable(obj):

-    return hasattr(obj, '__call__') or hasattr(obj, '__bases__')

-

-# silence Python 2.6 buggy warnings about Exception.message

-if _sys.version_info[:2] == (2, 6):

-    import warnings

-    warnings.filterwarnings(

-        action='ignore',

-        message='BaseException.message has been deprecated as of Python 2.6',

-        category=DeprecationWarning,

-        module='argparse')

-

-

-SUPPRESS = '==SUPPRESS=='

-

-OPTIONAL = '?'

-ZERO_OR_MORE = '*'

-ONE_OR_MORE = '+'

-PARSER = 'A...'

-REMAINDER = '...'

-

-# =============================

-# Utility functions and classes

-# =============================

-

-class _AttributeHolder(object):

-    """Abstract base class that provides __repr__.

-

-    The __repr__ method returns a string in the format::

-        ClassName(attr=name, attr=name, ...)

-    The attributes are determined either by a class-level attribute,

-    '_kwarg_names', or by inspecting the instance __dict__.

-    """

-

-    def __repr__(self):

-        type_name = type(self).__name__

-        arg_strings = []

-        for arg in self._get_args():

-            arg_strings.append(repr(arg))

-        for name, value in self._get_kwargs():

-            arg_strings.append('%s=%r' % (name, value))

-        return '%s(%s)' % (type_name, ', '.join(arg_strings))

-

-    def _get_kwargs(self):

-        return _sorted(self.__dict__.items())

-

-    def _get_args(self):

-        return []

-

-

-def _ensure_value(namespace, name, value):

-    if getattr(namespace, name, None) is None:

-        setattr(namespace, name, value)

-    return getattr(namespace, name)

-

-

-# ===============

-# Formatting Help

-# ===============

-

-class HelpFormatter(object):

-    """Formatter for generating usage messages and argument help strings.

-

-    Only the name of this class is considered a public API. All the methods

-    provided by the class are considered an implementation detail.

-    """

-

-    def __init__(self,

-                 prog,

-                 indent_increment=2,

-                 max_help_position=24,

-                 width=None):

-

-        # default setting for width

-        if width is None:

-            try:

-                width = int(_os.environ['COLUMNS'])

-            except (KeyError, ValueError):

-                width = 80

-            width -= 2

-

-        self._prog = prog

-        self._indent_increment = indent_increment

-        self._max_help_position = max_help_position

-        self._width = width

-

-        self._current_indent = 0

-        self._level = 0

-        self._action_max_length = 0

-

-        self._root_section = self._Section(self, None)

-        self._current_section = self._root_section

-

-        self._whitespace_matcher = _re.compile(r'\s+')

-        self._long_break_matcher = _re.compile(r'\n\n\n+')

-

-    # ===============================

-    # Section and indentation methods

-    # ===============================

-    def _indent(self):

-        self._current_indent += self._indent_increment

-        self._level += 1

-

-    def _dedent(self):

-        self._current_indent -= self._indent_increment

-        assert self._current_indent >= 0, 'Indent decreased below 0.'

-        self._level -= 1

-

-    class _Section(object):

-

-        def __init__(self, formatter, parent, heading=None):

-            self.formatter = formatter

-            self.parent = parent

-            self.heading = heading

-            self.items = []

-

-        def format_help(self):

-            # format the indented section

-            if self.parent is not None:

-                self.formatter._indent()

-            join = self.formatter._join_parts

-            for func, args in self.items:

-                func(*args)

-            item_help = join([func(*args) for func, args in self.items])

-            if self.parent is not None:

-                self.formatter._dedent()

-

-            # return nothing if the section was empty

-            if not item_help:

-                return ''

-

-            # add the heading if the section was non-empty

-            if self.heading is not SUPPRESS and self.heading is not None:

-                current_indent = self.formatter._current_indent

-                heading = '%*s%s:\n' % (current_indent, '', self.heading)

-            else:

-                heading = ''

-

-            # join the section-initial newline, the heading and the help

-            return join(['\n', heading, item_help, '\n'])

-

-    def _add_item(self, func, args):

-        self._current_section.items.append((func, args))

-

-    # ========================

-    # Message building methods

-    # ========================

-    def start_section(self, heading):

-        self._indent()

-        section = self._Section(self, self._current_section, heading)

-        self._add_item(section.format_help, [])

-        self._current_section = section

-

-    def end_section(self):

-        self._current_section = self._current_section.parent

-        self._dedent()

-

-    def add_text(self, text):

-        if text is not SUPPRESS and text is not None:

-            self._add_item(self._format_text, [text])

-

-    def add_usage(self, usage, actions, groups, prefix=None):

-        if usage is not SUPPRESS:

-            args = usage, actions, groups, prefix

-            self._add_item(self._format_usage, args)

-

-    def add_argument(self, action):

-        if action.help is not SUPPRESS:

-

-            # find all invocations

-            get_invocation = self._format_action_invocation

-            invocations = [get_invocation(action)]

-            for subaction in self._iter_indented_subactions(action):

-                invocations.append(get_invocation(subaction))

-

-            # update the maximum item length

-            invocation_length = max([len(s) for s in invocations])

-            action_length = invocation_length + self._current_indent

-            self._action_max_length = max(self._action_max_length,

-                                          action_length)

-

-            # add the item to the list

-            self._add_item(self._format_action, [action])

-

-    def add_arguments(self, actions):

-        for action in actions:

-            self.add_argument(action)

-

-    # =======================

-    # Help-formatting methods

-    # =======================

-    def format_help(self):

-        help = self._root_section.format_help()

-        if help:

-            help = self._long_break_matcher.sub('\n\n', help)

-            help = help.strip('\n') + '\n'

-        return help

-

-    def _join_parts(self, part_strings):

-        return ''.join([part

-                        for part in part_strings

-                        if part and part is not SUPPRESS])

-

-    def _format_usage(self, usage, actions, groups, prefix):

-        if prefix is None:

-            prefix = _('usage: ')

-

-        # if usage is specified, use that

-        if usage is not None:

-            usage = usage % dict(prog=self._prog)

-

-        # if no optionals or positionals are available, usage is just prog

-        elif usage is None and not actions:

-            usage = '%(prog)s' % dict(prog=self._prog)

-

-        # if optionals and positionals are available, calculate usage

-        elif usage is None:

-            prog = '%(prog)s' % dict(prog=self._prog)

-

-            # split optionals from positionals

-            optionals = []

-            positionals = []

-            for action in actions:

-                if action.option_strings:

-                    optionals.append(action)

-                else:

-                    positionals.append(action)

-

-            # build full usage string

-            format = self._format_actions_usage

-            action_usage = format(optionals + positionals, groups)

-            usage = ' '.join([s for s in [prog, action_usage] if s])

-

-            # wrap the usage parts if it's too long

-            text_width = self._width - self._current_indent

-            if len(prefix) + len(usage) > text_width:

-

-                # break usage into wrappable parts

-                part_regexp = r'\(.*?\)+|\[.*?\]+|\S+'

-                opt_usage = format(optionals, groups)

-                pos_usage = format(positionals, groups)

-                opt_parts = _re.findall(part_regexp, opt_usage)

-                pos_parts = _re.findall(part_regexp, pos_usage)

-                assert ' '.join(opt_parts) == opt_usage

-                assert ' '.join(pos_parts) == pos_usage

-

-                # helper for wrapping lines

-                def get_lines(parts, indent, prefix=None):

-                    lines = []

-                    line = []

-                    if prefix is not None:

-                        line_len = len(prefix) - 1

-                    else:

-                        line_len = len(indent) - 1

-                    for part in parts:

-                        if line_len + 1 + len(part) > text_width:

-                            lines.append(indent + ' '.join(line))

-                            line = []

-                            line_len = len(indent) - 1

-                        line.append(part)

-                        line_len += len(part) + 1

-                    if line:

-                        lines.append(indent + ' '.join(line))

-                    if prefix is not None:

-                        lines[0] = lines[0][len(indent):]

-                    return lines

-

-                # if prog is short, follow it with optionals or positionals

-                if len(prefix) + len(prog) <= 0.75 * text_width:

-                    indent = ' ' * (len(prefix) + len(prog) + 1)

-                    if opt_parts:

-                        lines = get_lines([prog] + opt_parts, indent, prefix)

-                        lines.extend(get_lines(pos_parts, indent))

-                    elif pos_parts:

-                        lines = get_lines([prog] + pos_parts, indent, prefix)

-                    else:

-                        lines = [prog]

-

-                # if prog is long, put it on its own line

-                else:

-                    indent = ' ' * len(prefix)

-                    parts = opt_parts + pos_parts

-                    lines = get_lines(parts, indent)

-                    if len(lines) > 1:

-                        lines = []

-                        lines.extend(get_lines(opt_parts, indent))

-                        lines.extend(get_lines(pos_parts, indent))

-                    lines = [prog] + lines

-

-                # join lines into usage

-                usage = '\n'.join(lines)

-

-        # prefix with 'usage:'

-        return '%s%s\n\n' % (prefix, usage)

-

-    def _format_actions_usage(self, actions, groups):

-        # find group indices and identify actions in groups

-        group_actions = _set()

-        inserts = {}

-        for group in groups:

-            try:

-                start = actions.index(group._group_actions[0])

-            except ValueError:

-                continue

-            else:

-                end = start + len(group._group_actions)

-                if actions[start:end] == group._group_actions:

-                    for action in group._group_actions:

-                        group_actions.add(action)

-                    if not group.required:

-                        inserts[start] = '['

-                        inserts[end] = ']'

-                    else:

-                        inserts[start] = '('

-                        inserts[end] = ')'

-                    for i in range(start + 1, end):

-                        inserts[i] = '|'

-

-        # collect all actions format strings

-        parts = []

-        for i, action in enumerate(actions):

-

-            # suppressed arguments are marked with None

-            # remove | separators for suppressed arguments

-            if action.help is SUPPRESS:

-                parts.append(None)

-                if inserts.get(i) == '|':

-                    inserts.pop(i)

-                elif inserts.get(i + 1) == '|':

-                    inserts.pop(i + 1)

-

-            # produce all arg strings

-            elif not action.option_strings:

-                part = self._format_args(action, action.dest)

-

-                # if it's in a group, strip the outer []

-                if action in group_actions:

-                    if part[0] == '[' and part[-1] == ']':

-                        part = part[1:-1]

-

-                # add the action string to the list

-                parts.append(part)

-

-            # produce the first way to invoke the option in brackets

-            else:

-                option_string = action.option_strings[0]

-

-                # if the Optional doesn't take a value, format is:

-                #    -s or --long

-                if action.nargs == 0:

-                    part = '%s' % option_string

-

-                # if the Optional takes a value, format is:

-                #    -s ARGS or --long ARGS

-                else:

-                    default = action.dest.upper()

-                    args_string = self._format_args(action, default)

-                    part = '%s %s' % (option_string, args_string)

-

-                # make it look optional if it's not required or in a group

-                if not action.required and action not in group_actions:

-                    part = '[%s]' % part

-

-                # add the action string to the list

-                parts.append(part)

-

-        # insert things at the necessary indices

-        for i in _sorted(inserts, reverse=True):

-            parts[i:i] = [inserts[i]]

-

-        # join all the action items with spaces

-        text = ' '.join([item for item in parts if item is not None])

-

-        # clean up separators for mutually exclusive groups

-        open = r'[\[(]'

-        close = r'[\])]'

-        text = _re.sub(r'(%s) ' % open, r'\1', text)

-        text = _re.sub(r' (%s)' % close, r'\1', text)

-        text = _re.sub(r'%s *%s' % (open, close), r'', text)

-        text = _re.sub(r'\(([^|]*)\)', r'\1', text)

-        text = text.strip()

-

-        # return the text

-        return text

-

-    def _format_text(self, text):

-        if '%(prog)' in text:

-            text = text % dict(prog=self._prog)

-        text_width = self._width - self._current_indent

-        indent = ' ' * self._current_indent

-        return self._fill_text(text, text_width, indent) + '\n\n'

-

-    def _format_action(self, action):

-        # determine the required width and the entry label

-        help_position = min(self._action_max_length + 2,

-                            self._max_help_position)

-        help_width = self._width - help_position

-        action_width = help_position - self._current_indent - 2

-        action_header = self._format_action_invocation(action)

-

-        # ho nelp; start on same line and add a final newline

-        if not action.help:

-            tup = self._current_indent, '', action_header

-            action_header = '%*s%s\n' % tup

-

-        # short action name; start on the same line and pad two spaces

-        elif len(action_header) <= action_width:

-            tup = self._current_indent, '', action_width, action_header

-            action_header = '%*s%-*s  ' % tup

-            indent_first = 0

-

-        # long action name; start on the next line

-        else:

-            tup = self._current_indent, '', action_header

-            action_header = '%*s%s\n' % tup

-            indent_first = help_position

-

-        # collect the pieces of the action help

-        parts = [action_header]

-

-        # if there was help for the action, add lines of help text

-        if action.help:

-            help_text = self._expand_help(action)

-            help_lines = self._split_lines(help_text, help_width)

-            parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))

-            for line in help_lines[1:]:

-                parts.append('%*s%s\n' % (help_position, '', line))

-

-        # or add a newline if the description doesn't end with one

-        elif not action_header.endswith('\n'):

-            parts.append('\n')

-

-        # if there are any sub-actions, add their help as well

-        for subaction in self._iter_indented_subactions(action):

-            parts.append(self._format_action(subaction))

-

-        # return a single string

-        return self._join_parts(parts)

-

-    def _format_action_invocation(self, action):

-        if not action.option_strings:

-            metavar, = self._metavar_formatter(action, action.dest)(1)

-            return metavar

-

-        else:

-            parts = []

-

-            # if the Optional doesn't take a value, format is:

-            #    -s, --long

-            if action.nargs == 0:

-                parts.extend(action.option_strings)

-

-            # if the Optional takes a value, format is:

-            #    -s ARGS, --long ARGS

-            else:

-                default = action.dest.upper()

-                args_string = self._format_args(action, default)

-                for option_string in action.option_strings:

-                    parts.append('%s %s' % (option_string, args_string))

-

-            return ', '.join(parts)

-

-    def _metavar_formatter(self, action, default_metavar):

-        if action.metavar is not None:

-            result = action.metavar

-        elif action.choices is not None:

-            choice_strs = [str(choice) for choice in action.choices]

-            result = '{%s}' % ','.join(choice_strs)

-        else:

-            result = default_metavar

-

-        def format(tuple_size):

-            if isinstance(result, tuple):

-                return result

-            else:

-                return (result, ) * tuple_size

-        return format

-

-    def _format_args(self, action, default_metavar):

-        get_metavar = self._metavar_formatter(action, default_metavar)

-        if action.nargs is None:

-            result = '%s' % get_metavar(1)

-        elif action.nargs == OPTIONAL:

-            result = '[%s]' % get_metavar(1)

-        elif action.nargs == ZERO_OR_MORE:

-            result = '[%s [%s ...]]' % get_metavar(2)

-        elif action.nargs == ONE_OR_MORE:

-            result = '%s [%s ...]' % get_metavar(2)

-        elif action.nargs == REMAINDER:

-            result = '...'

-        elif action.nargs == PARSER:

-            result = '%s ...' % get_metavar(1)

-        else:

-            formats = ['%s' for _ in range(action.nargs)]

-            result = ' '.join(formats) % get_metavar(action.nargs)

-        return result

-

-    def _expand_help(self, action):

-        params = dict(vars(action), prog=self._prog)

-        for name in list(params):

-            if params[name] is SUPPRESS:

-                del params[name]

-        for name in list(params):

-            if hasattr(params[name], '__name__'):

-                params[name] = params[name].__name__

-        if params.get('choices') is not None:

-            choices_str = ', '.join([str(c) for c in params['choices']])

-            params['choices'] = choices_str

-        return self._get_help_string(action) % params

-

-    def _iter_indented_subactions(self, action):

-        try:

-            get_subactions = action._get_subactions

-        except AttributeError:

-            pass

-        else:

-            self._indent()

-            for subaction in get_subactions():

-                yield subaction

-            self._dedent()

-

-    def _split_lines(self, text, width):

-        text = self._whitespace_matcher.sub(' ', text).strip()

-        return _textwrap.wrap(text, width)

-

-    def _fill_text(self, text, width, indent):

-        text = self._whitespace_matcher.sub(' ', text).strip()

-        return _textwrap.fill(text, width, initial_indent=indent,

-                                           subsequent_indent=indent)

-

-    def _get_help_string(self, action):

-        return action.help

-

-

-class RawDescriptionHelpFormatter(HelpFormatter):

-    """Help message formatter which retains any formatting in descriptions.

-

-    Only the name of this class is considered a public API. All the methods

-    provided by the class are considered an implementation detail.

-    """

-

-    def _fill_text(self, text, width, indent):

-        return ''.join([indent + line for line in text.splitlines(True)])

-

-

-class RawTextHelpFormatter(RawDescriptionHelpFormatter):

-    """Help message formatter which retains formatting of all help text.

-

-    Only the name of this class is considered a public API. All the methods

-    provided by the class are considered an implementation detail.

-    """

-

-    def _split_lines(self, text, width):

-        return text.splitlines()

-

-

-class ArgumentDefaultsHelpFormatter(HelpFormatter):

-    """Help message formatter which adds default values to argument help.

-

-    Only the name of this class is considered a public API. All the methods

-    provided by the class are considered an implementation detail.

-    """

-

-    def _get_help_string(self, action):

-        help = action.help

-        if '%(default)' not in action.help:

-            if action.default is not SUPPRESS:

-                defaulting_nargs = [OPTIONAL, ZERO_OR_MORE]

-                if action.option_strings or action.nargs in defaulting_nargs:

-                    help += ' (default: %(default)s)'

-        return help

-

-

-# =====================

-# Options and Arguments

-# =====================

-

-def _get_action_name(argument):

-    if argument is None:

-        return None

-    elif argument.option_strings:

-        return  '/'.join(argument.option_strings)

-    elif argument.metavar not in (None, SUPPRESS):

-        return argument.metavar

-    elif argument.dest not in (None, SUPPRESS):

-        return argument.dest

-    else:

-        return None

-

-

-class ArgumentError(Exception):

-    """An error from creating or using an argument (optional or positional).

-

-    The string value of this exception is the message, augmented with

-    information about the argument that caused it.

-    """

-

-    def __init__(self, argument, message):

-        self.argument_name = _get_action_name(argument)

-        self.message = message

-

-    def __str__(self):

-        if self.argument_name is None:

-            format = '%(message)s'

-        else:

-            format = 'argument %(argument_name)s: %(message)s'

-        return format % dict(message=self.message,

-                             argument_name=self.argument_name)

-

-

-class ArgumentTypeError(Exception):

-    """An error from trying to convert a command line string to a type."""

-    pass

-

-

-# ==============

-# Action classes

-# ==============

-

-class Action(_AttributeHolder):

-    """Information about how to convert command line strings to Python objects.

-

-    Action objects are used by an ArgumentParser to represent the information

-    needed to parse a single argument from one or more strings from the

-    command line. The keyword arguments to the Action constructor are also

-    all attributes of Action instances.

-

-    Keyword Arguments:

-

-        - option_strings -- A list of command-line option strings which

-            should be associated with this action.

-

-        - dest -- The name of the attribute to hold the created object(s)

-

-        - nargs -- The number of command-line arguments that should be

-            consumed. By default, one argument will be consumed and a single

-            value will be produced.  Other values include:

-                - N (an integer) consumes N arguments (and produces a list)

-                - '?' consumes zero or one arguments

-                - '*' consumes zero or more arguments (and produces a list)

-                - '+' consumes one or more arguments (and produces a list)

-            Note that the difference between the default and nargs=1 is that

-            with the default, a single value will be produced, while with

-            nargs=1, a list containing a single value will be produced.

-

-        - const -- The value to be produced if the option is specified and the

-            option uses an action that takes no values.

-

-        - default -- The value to be produced if the option is not specified.

-

-        - type -- The type which the command-line arguments should be converted

-            to, should be one of 'string', 'int', 'float', 'complex' or a

-            callable object that accepts a single string argument. If None,

-            'string' is assumed.

-

-        - choices -- A container of values that should be allowed. If not None,

-            after a command-line argument has been converted to the appropriate

-            type, an exception will be raised if it is not a member of this

-            collection.

-

-        - required -- True if the action must always be specified at the

-            command line. This is only meaningful for optional command-line

-            arguments.

-

-        - help -- The help string describing the argument.

-

-        - metavar -- The name to be used for the option's argument with the

-            help string. If None, the 'dest' value will be used as the name.

-    """

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 nargs=None,

-                 const=None,

-                 default=None,

-                 type=None,

-                 choices=None,

-                 required=False,

-                 help=None,

-                 metavar=None):

-        self.option_strings = option_strings

-        self.dest = dest

-        self.nargs = nargs

-        self.const = const

-        self.default = default

-        self.type = type

-        self.choices = choices

-        self.required = required

-        self.help = help

-        self.metavar = metavar

-

-    def _get_kwargs(self):

-        names = [

-            'option_strings',

-            'dest',

-            'nargs',

-            'const',

-            'default',

-            'type',

-            'choices',

-            'help',

-            'metavar',

-        ]

-        return [(name, getattr(self, name)) for name in names]

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        raise NotImplementedError(_('.__call__() not defined'))

-

-

-class _StoreAction(Action):

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 nargs=None,

-                 const=None,

-                 default=None,

-                 type=None,

-                 choices=None,

-                 required=False,

-                 help=None,

-                 metavar=None):

-        if nargs == 0:

-            raise ValueError('nargs for store actions must be > 0; if you '

-                             'have nothing to store, actions such as store '

-                             'true or store const may be more appropriate')

-        if const is not None and nargs != OPTIONAL:

-            raise ValueError('nargs must be %r to supply const' % OPTIONAL)

-        super(_StoreAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            nargs=nargs,

-            const=const,

-            default=default,

-            type=type,

-            choices=choices,

-            required=required,

-            help=help,

-            metavar=metavar)

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        setattr(namespace, self.dest, values)

-

-

-class _StoreConstAction(Action):

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 const,

-                 default=None,

-                 required=False,

-                 help=None,

-                 metavar=None):

-        super(_StoreConstAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            nargs=0,

-            const=const,

-            default=default,

-            required=required,

-            help=help)

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        setattr(namespace, self.dest, self.const)

-

-

-class _StoreTrueAction(_StoreConstAction):

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 default=False,

-                 required=False,

-                 help=None):

-        super(_StoreTrueAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            const=True,

-            default=default,

-            required=required,

-            help=help)

-

-

-class _StoreFalseAction(_StoreConstAction):

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 default=True,

-                 required=False,

-                 help=None):

-        super(_StoreFalseAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            const=False,

-            default=default,

-            required=required,

-            help=help)

-

-

-class _AppendAction(Action):

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 nargs=None,

-                 const=None,

-                 default=None,

-                 type=None,

-                 choices=None,

-                 required=False,

-                 help=None,

-                 metavar=None):

-        if nargs == 0:

-            raise ValueError('nargs for append actions must be > 0; if arg '

-                             'strings are not supplying the value to append, '

-                             'the append const action may be more appropriate')

-        if const is not None and nargs != OPTIONAL:

-            raise ValueError('nargs must be %r to supply const' % OPTIONAL)

-        super(_AppendAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            nargs=nargs,

-            const=const,

-            default=default,

-            type=type,

-            choices=choices,

-            required=required,

-            help=help,

-            metavar=metavar)

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        items = _copy.copy(_ensure_value(namespace, self.dest, []))

-        items.append(values)

-        setattr(namespace, self.dest, items)

-

-

-class _AppendConstAction(Action):

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 const,

-                 default=None,

-                 required=False,

-                 help=None,

-                 metavar=None):

-        super(_AppendConstAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            nargs=0,

-            const=const,

-            default=default,

-            required=required,

-            help=help,

-            metavar=metavar)

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        items = _copy.copy(_ensure_value(namespace, self.dest, []))

-        items.append(self.const)

-        setattr(namespace, self.dest, items)

-

-

-class _CountAction(Action):

-

-    def __init__(self,

-                 option_strings,

-                 dest,

-                 default=None,

-                 required=False,

-                 help=None):

-        super(_CountAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            nargs=0,

-            default=default,

-            required=required,

-            help=help)

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        new_count = _ensure_value(namespace, self.dest, 0) + 1

-        setattr(namespace, self.dest, new_count)

-

-

-class _HelpAction(Action):

-

-    def __init__(self,

-                 option_strings,

-                 dest=SUPPRESS,

-                 default=SUPPRESS,

-                 help=None):

-        super(_HelpAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            default=default,

-            nargs=0,

-            help=help)

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        parser.print_help()

-        parser.exit()

-

-

-class _VersionAction(Action):

-

-    def __init__(self,

-                 option_strings,

-                 version=None,

-                 dest=SUPPRESS,

-                 default=SUPPRESS,

-                 help=None):

-        super(_VersionAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            default=default,

-            nargs=0,

-            help=help)

-        self.version = version

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        version = self.version

-        if version is None:

-            version = parser.version

-        formatter = parser._get_formatter()

-        formatter.add_text(version)

-        parser.exit(message=formatter.format_help())

-

-

-class _SubParsersAction(Action):

-

-    class _ChoicesPseudoAction(Action):

-

-        def __init__(self, name, help):

-            sup = super(_SubParsersAction._ChoicesPseudoAction, self)

-            sup.__init__(option_strings=[], dest=name, help=help)

-

-    def __init__(self,

-                 option_strings,

-                 prog,

-                 parser_class,

-                 dest=SUPPRESS,

-                 help=None,

-                 metavar=None):

-

-        self._prog_prefix = prog

-        self._parser_class = parser_class

-        self._name_parser_map = {}

-        self._choices_actions = []

-

-        super(_SubParsersAction, self).__init__(

-            option_strings=option_strings,

-            dest=dest,

-            nargs=PARSER,

-            choices=self._name_parser_map,

-            help=help,

-            metavar=metavar)

-

-    def add_parser(self, name, **kwargs):

-        # set prog from the existing prefix

-        if kwargs.get('prog') is None:

-            kwargs['prog'] = '%s %s' % (self._prog_prefix, name)

-

-        # create a pseudo-action to hold the choice help

-        if 'help' in kwargs:

-            help = kwargs.pop('help')

-            choice_action = self._ChoicesPseudoAction(name, help)

-            self._choices_actions.append(choice_action)

-

-        # create the parser and add it to the map

-        parser = self._parser_class(**kwargs)

-        self._name_parser_map[name] = parser

-        return parser

-

-    def _get_subactions(self):

-        return self._choices_actions

-

-    def __call__(self, parser, namespace, values, option_string=None):

-        parser_name = values[0]

-        arg_strings = values[1:]

-

-        # set the parser name if requested

-        if self.dest is not SUPPRESS:

-            setattr(namespace, self.dest, parser_name)

-

-        # select the parser

-        try:

-            parser = self._name_parser_map[parser_name]

-        except KeyError:

-            tup = parser_name, ', '.join(self._name_parser_map)

-            msg = _('unknown parser %r (choices: %s)' % tup)

-            raise ArgumentError(self, msg)

-

-        # parse all the remaining options into the namespace

-        parser.parse_args(arg_strings, namespace)

-

-

-# ==============

-# Type classes

-# ==============

-

-class FileType(object):

-    """Factory for creating file object types

-

-    Instances of FileType are typically passed as type= arguments to the

-    ArgumentParser add_argument() method.

-

-    Keyword Arguments:

-        - mode -- A string indicating how the file is to be opened. Accepts the

-            same values as the builtin open() function.

-        - bufsize -- The file's desired buffer size. Accepts the same values as

-            the builtin open() function.

-    """

-

-    def __init__(self, mode='r', bufsize=None):

-        self._mode = mode

-        self._bufsize = bufsize

-

-    def __call__(self, string):

-        # the special argument "-" means sys.std{in,out}

-        if string == '-':

-            if 'r' in self._mode:

-                return _sys.stdin

-            elif 'w' in self._mode:

-                return _sys.stdout

-            else:

-                msg = _('argument "-" with mode %r' % self._mode)

-                raise ValueError(msg)

-

-        # all other arguments are used as file names

-        if self._bufsize:

-            return open(string, self._mode, self._bufsize)

-        else:

-            return open(string, self._mode)

-

-    def __repr__(self):

-        args = [self._mode, self._bufsize]

-        args_str = ', '.join([repr(arg) for arg in args if arg is not None])

-        return '%s(%s)' % (type(self).__name__, args_str)

-

-# ===========================

-# Optional and Positional Parsing

-# ===========================

-

-class Namespace(_AttributeHolder):

-    """Simple object for storing attributes.

-

-    Implements equality by attribute names and values, and provides a simple

-    string representation.

-    """

-

-    def __init__(self, **kwargs):

-        for name in kwargs:

-            setattr(self, name, kwargs[name])

-

-    def __eq__(self, other):

-        return vars(self) == vars(other)

-

-    def __ne__(self, other):

-        return not (self == other)

-

-    def __contains__(self, key):

-        return key in self.__dict__

-

-

-class _ActionsContainer(object):

-

-    def __init__(self,

-                 description,

-                 prefix_chars,

-                 argument_default,

-                 conflict_handler):

-        super(_ActionsContainer, self).__init__()

-

-        self.description = description

-        self.argument_default = argument_default

-        self.prefix_chars = prefix_chars

-        self.conflict_handler = conflict_handler

-

-        # set up registries

-        self._registries = {}

-

-        # register actions

-        self.register('action', None, _StoreAction)

-        self.register('action', 'store', _StoreAction)

-        self.register('action', 'store_const', _StoreConstAction)

-        self.register('action', 'store_true', _StoreTrueAction)

-        self.register('action', 'store_false', _StoreFalseAction)

-        self.register('action', 'append', _AppendAction)

-        self.register('action', 'append_const', _AppendConstAction)

-        self.register('action', 'count', _CountAction)

-        self.register('action', 'help', _HelpAction)

-        self.register('action', 'version', _VersionAction)

-        self.register('action', 'parsers', _SubParsersAction)

-

-        # raise an exception if the conflict handler is invalid

-        self._get_handler()

-

-        # action storage

-        self._actions = []

-        self._option_string_actions = {}

-

-        # groups

-        self._action_groups = []

-        self._mutually_exclusive_groups = []

-

-        # defaults storage

-        self._defaults = {}

-

-        # determines whether an "option" looks like a negative number

-        self._negative_number_matcher = _re.compile(r'^-\d+$|^-\d*\.\d+$')

-

-        # whether or not there are any optionals that look like negative

-        # numbers -- uses a list so it can be shared and edited

-        self._has_negative_number_optionals = []

-

-    # ====================

-    # Registration methods

-    # ====================

-    def register(self, registry_name, value, object):

-        registry = self._registries.setdefault(registry_name, {})

-        registry[value] = object

-

-    def _registry_get(self, registry_name, value, default=None):

-        return self._registries[registry_name].get(value, default)

-

-    # ==================================

-    # Namespace default accessor methods

-    # ==================================

-    def set_defaults(self, **kwargs):

-        self._defaults.update(kwargs)

-

-        # if these defaults match any existing arguments, replace

-        # the previous default on the object with the new one

-        for action in self._actions:

-            if action.dest in kwargs:

-                action.default = kwargs[action.dest]

-

-    def get_default(self, dest):

-        for action in self._actions:

-            if action.dest == dest and action.default is not None:

-                return action.default

-        return self._defaults.get(dest, None)

-

-

-    # =======================

-    # Adding argument actions

-    # =======================

-    def add_argument(self, *args, **kwargs):

-        """

-        add_argument(dest, ..., name=value, ...)

-        add_argument(option_string, option_string, ..., name=value, ...)

-        """

-

-        # if no positional args are supplied or only one is supplied and

-        # it doesn't look like an option string, parse a positional

-        # argument

-        chars = self.prefix_chars

-        if not args or len(args) == 1 and args[0][0] not in chars:

-            if args and 'dest' in kwargs:

-                raise ValueError('dest supplied twice for positional argument')

-            kwargs = self._get_positional_kwargs(*args, **kwargs)

-

-        # otherwise, we're adding an optional argument

-        else:

-            kwargs = self._get_optional_kwargs(*args, **kwargs)

-

-        # if no default was supplied, use the parser-level default

-        if 'default' not in kwargs:

-            dest = kwargs['dest']

-            if dest in self._defaults:

-                kwargs['default'] = self._defaults[dest]

-            elif self.argument_default is not None:

-                kwargs['default'] = self.argument_default

-

-        # create the action object, and add it to the parser

-        action_class = self._pop_action_class(kwargs)

-        if not _callable(action_class):

-            raise ValueError('unknown action "%s"' % action_class)

-        action = action_class(**kwargs)

-

-        # raise an error if the action type is not callable

-        type_func = self._registry_get('type', action.type, action.type)

-        if not _callable(type_func):

-            raise ValueError('%r is not callable' % type_func)

-

-        return self._add_action(action)

-

-    def add_argument_group(self, *args, **kwargs):

-        group = _ArgumentGroup(self, *args, **kwargs)

-        self._action_groups.append(group)

-        return group

-

-    def add_mutually_exclusive_group(self, **kwargs):

-        group = _MutuallyExclusiveGroup(self, **kwargs)

-        self._mutually_exclusive_groups.append(group)

-        return group

-

-    def _add_action(self, action):

-        # resolve any conflicts

-        self._check_conflict(action)

-

-        # add to actions list

-        self._actions.append(action)

-        action.container = self

-

-        # index the action by any option strings it has

-        for option_string in action.option_strings:

-            self._option_string_actions[option_string] = action

-

-        # set the flag if any option strings look like negative numbers

-        for option_string in action.option_strings:

-            if self._negative_number_matcher.match(option_string):

-                if not self._has_negative_number_optionals:

-                    self._has_negative_number_optionals.append(True)

-

-        # return the created action

-        return action

-

-    def _remove_action(self, action):

-        self._actions.remove(action)

-

-    def _add_container_actions(self, container):

-        # collect groups by titles

-        title_group_map = {}

-        for group in self._action_groups:

-            if group.title in title_group_map:

-                msg = _('cannot merge actions - two groups are named %r')

-                raise ValueError(msg % (group.title))

-            title_group_map[group.title] = group

-

-        # map each action to its group

-        group_map = {}

-        for group in container._action_groups:

-

-            # if a group with the title exists, use that, otherwise

-            # create a new group matching the container's group

-            if group.title not in title_group_map:

-                title_group_map[group.title] = self.add_argument_group(

-                    title=group.title,

-                    description=group.description,

-                    conflict_handler=group.conflict_handler)

-

-            # map the actions to their new group

-            for action in group._group_actions:

-                group_map[action] = title_group_map[group.title]

-

-        # add container's mutually exclusive groups

-        # NOTE: if add_mutually_exclusive_group ever gains title= and

-        # description= then this code will need to be expanded as above

-        for group in container._mutually_exclusive_groups:

-            mutex_group = self.add_mutually_exclusive_group(

-                required=group.required)

-

-            # map the actions to their new mutex group

-            for action in group._group_actions:

-                group_map[action] = mutex_group

-

-        # add all actions to this container or their group

-        for action in container._actions:

-            group_map.get(action, self)._add_action(action)

-

-    def _get_positional_kwargs(self, dest, **kwargs):

-        # make sure required is not specified

-        if 'required' in kwargs:

-            msg = _("'required' is an invalid argument for positionals")

-            raise TypeError(msg)

-

-        # mark positional arguments as required if at least one is

-        # always required

-        if kwargs.get('nargs') not in [OPTIONAL, ZERO_OR_MORE]:

-            kwargs['required'] = True

-        if kwargs.get('nargs') == ZERO_OR_MORE and 'default' not in kwargs:

-            kwargs['required'] = True

-

-        # return the keyword arguments with no option strings

-        return dict(kwargs, dest=dest, option_strings=[])

-

-    def _get_optional_kwargs(self, *args, **kwargs):

-        # determine short and long option strings

-        option_strings = []

-        long_option_strings = []

-        for option_string in args:

-            # error on strings that don't start with an appropriate prefix

-            if not option_string[0] in self.prefix_chars:

-                msg = _('invalid option string %r: '

-                        'must start with a character %r')

-                tup = option_string, self.prefix_chars

-                raise ValueError(msg % tup)

-

-            # strings starting with two prefix characters are long options

-            option_strings.append(option_string)

-            if option_string[0] in self.prefix_chars:

-                if len(option_string) > 1:

-                    if option_string[1] in self.prefix_chars:

-                        long_option_strings.append(option_string)

-

-        # infer destination, '--foo-bar' -> 'foo_bar' and '-x' -> 'x'

-        dest = kwargs.pop('dest', None)

-        if dest is None:

-            if long_option_strings:

-                dest_option_string = long_option_strings[0]

-            else:

-                dest_option_string = option_strings[0]

-            dest = dest_option_string.lstrip(self.prefix_chars)

-            if not dest:

-                msg = _('dest= is required for options like %r')

-                raise ValueError(msg % option_string)

-            dest = dest.replace('-', '_')

-

-        # return the updated keyword arguments

-        return dict(kwargs, dest=dest, option_strings=option_strings)

-

-    def _pop_action_class(self, kwargs, default=None):

-        action = kwargs.pop('action', default)

-        return self._registry_get('action', action, action)

-

-    def _get_handler(self):

-        # determine function from conflict handler string

-        handler_func_name = '_handle_conflict_%s' % self.conflict_handler

-        try:

-            return getattr(self, handler_func_name)

-        except AttributeError:

-            msg = _('invalid conflict_resolution value: %r')

-            raise ValueError(msg % self.conflict_handler)

-

-    def _check_conflict(self, action):

-

-        # find all options that conflict with this option

-        confl_optionals = []

-        for option_string in action.option_strings:

-            if option_string in self._option_string_actions:

-                confl_optional = self._option_string_actions[option_string]

-                confl_optionals.append((option_string, confl_optional))

-

-        # resolve any conflicts

-        if confl_optionals:

-            conflict_handler = self._get_handler()

-            conflict_handler(action, confl_optionals)

-

-    def _handle_conflict_error(self, action, conflicting_actions):

-        message = _('conflicting option string(s): %s')

-        conflict_string = ', '.join([option_string

-                                     for option_string, action

-                                     in conflicting_actions])

-        raise ArgumentError(action, message % conflict_string)

-

-    def _handle_conflict_resolve(self, action, conflicting_actions):

-

-        # remove all conflicting options

-        for option_string, action in conflicting_actions:

-

-            # remove the conflicting option

-            action.option_strings.remove(option_string)

-            self._option_string_actions.pop(option_string, None)

-

-            # if the option now has no option string, remove it from the

-            # container holding it

-            if not action.option_strings:

-                action.container._remove_action(action)

-

-

-class _ArgumentGroup(_ActionsContainer):

-

-    def __init__(self, container, title=None, description=None, **kwargs):

-        # add any missing keyword arguments by checking the container

-        update = kwargs.setdefault

-        update('conflict_handler', container.conflict_handler)

-        update('prefix_chars', container.prefix_chars)

-        update('argument_default', container.argument_default)

-        super_init = super(_ArgumentGroup, self).__init__

-        super_init(description=description, **kwargs)

-

-        # group attributes

-        self.title = title

-        self._group_actions = []

-

-        # share most attributes with the container

-        self._registries = container._registries

-        self._actions = container._actions

-        self._option_string_actions = container._option_string_actions

-        self._defaults = container._defaults

-        self._has_negative_number_optionals = \

-            container._has_negative_number_optionals

-

-    def _add_action(self, action):

-        action = super(_ArgumentGroup, self)._add_action(action)

-        self._group_actions.append(action)

-        return action

-

-    def _remove_action(self, action):

-        super(_ArgumentGroup, self)._remove_action(action)

-        self._group_actions.remove(action)

-

-

-class _MutuallyExclusiveGroup(_ArgumentGroup):

-

-    def __init__(self, container, required=False):

-        super(_MutuallyExclusiveGroup, self).__init__(container)

-        self.required = required

-        self._container = container

-

-    def _add_action(self, action):

-        if action.required:

-            msg = _('mutually exclusive arguments must be optional')

-            raise ValueError(msg)

-        action = self._container._add_action(action)

-        self._group_actions.append(action)

-        return action

-

-    def _remove_action(self, action):

-        self._container._remove_action(action)

-        self._group_actions.remove(action)

-

-

-class ArgumentParser(_AttributeHolder, _ActionsContainer):

-    """Object for parsing command line strings into Python objects.

-

-    Keyword Arguments:

-        - prog -- The name of the program (default: sys.argv[0])

-        - usage -- A usage message (default: auto-generated from arguments)

-        - description -- A description of what the program does

-        - epilog -- Text following the argument descriptions

-        - parents -- Parsers whose arguments should be copied into this one

-        - formatter_class -- HelpFormatter class for printing help messages

-        - prefix_chars -- Characters that prefix optional arguments

-        - fromfile_prefix_chars -- Characters that prefix files containing

-            additional arguments

-        - argument_default -- The default value for all arguments

-        - conflict_handler -- String indicating how to handle conflicts

-        - add_help -- Add a -h/-help option

-    """

-

-    def __init__(self,

-                 prog=None,

-                 usage=None,

-                 description=None,

-                 epilog=None,

-                 version=None,

-                 parents=[],

-                 formatter_class=HelpFormatter,

-                 prefix_chars='-',

-                 fromfile_prefix_chars=None,

-                 argument_default=None,

-                 conflict_handler='error',

-                 add_help=True):

-

-        if version is not None:

-            import warnings

-            warnings.warn(

-                """The "version" argument to ArgumentParser is deprecated. """

-                """Please use """

-                """"add_argument(..., action='version', version="N", ...)" """

-                """instead""", DeprecationWarning)

-

-        superinit = super(ArgumentParser, self).__init__

-        superinit(description=description,

-                  prefix_chars=prefix_chars,

-                  argument_default=argument_default,

-                  conflict_handler=conflict_handler)

-

-        # default setting for prog

-        if prog is None:

-            prog = _os.path.basename(_sys.argv[0])

-

-        self.prog = prog

-        self.usage = usage

-        self.epilog = epilog

-        self.version = version

-        self.formatter_class = formatter_class

-        self.fromfile_prefix_chars = fromfile_prefix_chars

-        self.add_help = add_help

-

-        add_group = self.add_argument_group

-        self._positionals = add_group(_('positional arguments'))

-        self._optionals = add_group(_('optional arguments'))

-        self._subparsers = None

-

-        # register types

-        def identity(string):

-            return string

-        self.register('type', None, identity)

-

-        # add help and version arguments if necessary

-        # (using explicit default to override global argument_default)

-        if self.add_help:

-            self.add_argument(

-                '-h', '--help', action='help', default=SUPPRESS,

-                help=_('show this help message and exit'))

-        if self.version:

-            self.add_argument(

-                '-v', '--version', action='version', default=SUPPRESS,

-                version=self.version,

-                help=_("show program's version number and exit"))

-

-        # add parent arguments and defaults

-        for parent in parents:

-            self._add_container_actions(parent)

-            try:

-                defaults = parent._defaults

-            except AttributeError:

-                pass

-            else:

-                self._defaults.update(defaults)

-

-    # =======================

-    # Pretty __repr__ methods

-    # =======================

-    def _get_kwargs(self):

-        names = [

-            'prog',

-            'usage',

-            'description',

-            'version',

-            'formatter_class',

-            'conflict_handler',

-            'add_help',

-        ]

-        return [(name, getattr(self, name)) for name in names]

-

-    # ==================================

-    # Optional/Positional adding methods

-    # ==================================

-    def add_subparsers(self, **kwargs):

-        if self._subparsers is not None:

-            self.error(_('cannot have multiple subparser arguments'))

-

-        # add the parser class to the arguments if it's not present

-        kwargs.setdefault('parser_class', type(self))

-

-        if 'title' in kwargs or 'description' in kwargs:

-            title = _(kwargs.pop('title', 'subcommands'))

-            description = _(kwargs.pop('description', None))

-            self._subparsers = self.add_argument_group(title, description)

-        else:

-            self._subparsers = self._positionals

-

-        # prog defaults to the usage message of this parser, skipping

-        # optional arguments and with no "usage:" prefix

-        if kwargs.get('prog') is None:

-            formatter = self._get_formatter()

-            positionals = self._get_positional_actions()

-            groups = self._mutually_exclusive_groups

-            formatter.add_usage(self.usage, positionals, groups, '')

-            kwargs['prog'] = formatter.format_help().strip()

-

-        # create the parsers action and add it to the positionals list

-        parsers_class = self._pop_action_class(kwargs, 'parsers')

-        action = parsers_class(option_strings=[], **kwargs)

-        self._subparsers._add_action(action)

-

-        # return the created parsers action

-        return action

-

-    def _add_action(self, action):

-        if action.option_strings:

-            self._optionals._add_action(action)

-        else:

-            self._positionals._add_action(action)

-        return action

-

-    def _get_optional_actions(self):

-        return [action

-                for action in self._actions

-                if action.option_strings]

-

-    def _get_positional_actions(self):

-        return [action

-                for action in self._actions

-                if not action.option_strings]

-

-    # =====================================

-    # Command line argument parsing methods

-    # =====================================

-    def parse_args(self, args=None, namespace=None):

-        args, argv = self.parse_known_args(args, namespace)

-        if argv:

-            msg = _('unrecognized arguments: %s')

-            self.error(msg % ' '.join(argv))

-        return args

-

-    def parse_known_args(self, args=None, namespace=None):

-        # args default to the system args

-        if args is None:

-            args = _sys.argv[1:]

-

-        # default Namespace built from parser defaults

-        if namespace is None:

-            namespace = Namespace()

-

-        # add any action defaults that aren't present

-        for action in self._actions:

-            if action.dest is not SUPPRESS:

-                if not hasattr(namespace, action.dest):

-                    if action.default is not SUPPRESS:

-                        default = action.default

-                        if isinstance(action.default, _basestring):

-                            default = self._get_value(action, default)

-                        setattr(namespace, action.dest, default)

-

-        # add any parser defaults that aren't present

-        for dest in self._defaults:

-            if not hasattr(namespace, dest):

-                setattr(namespace, dest, self._defaults[dest])

-

-        # parse the arguments and exit if there are any errors

-        try:

-            return self._parse_known_args(args, namespace)

-        except ArgumentError:

-            err = _sys.exc_info()[1]

-            self.error(str(err))

-

-    def _parse_known_args(self, arg_strings, namespace):

-        # replace arg strings that are file references

-        if self.fromfile_prefix_chars is not None:

-            arg_strings = self._read_args_from_files(arg_strings)

-

-        # map all mutually exclusive arguments to the other arguments

-        # they can't occur with

-        action_conflicts = {}

-        for mutex_group in self._mutually_exclusive_groups:

-            group_actions = mutex_group._group_actions

-            for i, mutex_action in enumerate(mutex_group._group_actions):

-                conflicts = action_conflicts.setdefault(mutex_action, [])

-                conflicts.extend(group_actions[:i])

-                conflicts.extend(group_actions[i + 1:])

-

-        # find all option indices, and determine the arg_string_pattern

-        # which has an 'O' if there is an option at an index,

-        # an 'A' if there is an argument, or a '-' if there is a '--'

-        option_string_indices = {}

-        arg_string_pattern_parts = []

-        arg_strings_iter = iter(arg_strings)

-        for i, arg_string in enumerate(arg_strings_iter):

-

-            # all args after -- are non-options

-            if arg_string == '--':

-                arg_string_pattern_parts.append('-')

-                for arg_string in arg_strings_iter:

-                    arg_string_pattern_parts.append('A')

-

-            # otherwise, add the arg to the arg strings

-            # and note the index if it was an option

-            else:

-                option_tuple = self._parse_optional(arg_string)

-                if option_tuple is None:

-                    pattern = 'A'

-                else:

-                    option_string_indices[i] = option_tuple

-                    pattern = 'O'

-                arg_string_pattern_parts.append(pattern)

-

-        # join the pieces together to form the pattern

-        arg_strings_pattern = ''.join(arg_string_pattern_parts)

-

-        # converts arg strings to the appropriate and then takes the action

-        seen_actions = _set()

-        seen_non_default_actions = _set()

-

-        def take_action(action, argument_strings, option_string=None):

-            seen_actions.add(action)

-            argument_values = self._get_values(action, argument_strings)

-

-            # error if this argument is not allowed with other previously

-            # seen arguments, assuming that actions that use the default

-            # value don't really count as "present"

-            if argument_values is not action.default:

-                seen_non_default_actions.add(action)

-                for conflict_action in action_conflicts.get(action, []):

-                    if conflict_action in seen_non_default_actions:

-                        msg = _('not allowed with argument %s')

-                        action_name = _get_action_name(conflict_action)

-                        raise ArgumentError(action, msg % action_name)

-

-            # take the action if we didn't receive a SUPPRESS value

-            # (e.g. from a default)

-            if argument_values is not SUPPRESS:

-                action(self, namespace, argument_values, option_string)

-

-        # function to convert arg_strings into an optional action

-        def consume_optional(start_index):

-

-            # get the optional identified at this index

-            option_tuple = option_string_indices[start_index]

-            action, option_string, explicit_arg = option_tuple

-

-            # identify additional optionals in the same arg string

-            # (e.g. -xyz is the same as -x -y -z if no args are required)

-            match_argument = self._match_argument

-            action_tuples = []

-            while True:

-

-                # if we found no optional action, skip it

-                if action is None:

-                    extras.append(arg_strings[start_index])

-                    return start_index + 1

-

-                # if there is an explicit argument, try to match the

-                # optional's string arguments to only this

-                if explicit_arg is not None:

-                    arg_count = match_argument(action, 'A')

-

-                    # if the action is a single-dash option and takes no

-                    # arguments, try to parse more single-dash options out

-                    # of the tail of the option string

-                    chars = self.prefix_chars

-                    if arg_count == 0 and option_string[1] not in chars:

-                        action_tuples.append((action, [], option_string))

-                        for char in self.prefix_chars:

-                            option_string = char + explicit_arg[0]

-                            explicit_arg = explicit_arg[1:] or None

-                            optionals_map = self._option_string_actions

-                            if option_string in optionals_map:

-                                action = optionals_map[option_string]

-                                break

-                        else:

-                            msg = _('ignored explicit argument %r')

-                            raise ArgumentError(action, msg % explicit_arg)

-

-                    # if the action expect exactly one argument, we've

-                    # successfully matched the option; exit the loop

-                    elif arg_count == 1:

-                        stop = start_index + 1

-                        args = [explicit_arg]

-                        action_tuples.append((action, args, option_string))

-                        break

-

-                    # error if a double-dash option did not use the

-                    # explicit argument

-                    else:

-                        msg = _('ignored explicit argument %r')

-                        raise ArgumentError(action, msg % explicit_arg)

-

-                # if there is no explicit argument, try to match the

-                # optional's string arguments with the following strings

-                # if successful, exit the loop

-                else:

-                    start = start_index + 1

-                    selected_patterns = arg_strings_pattern[start:]

-                    arg_count = match_argument(action, selected_patterns)

-                    stop = start + arg_count

-                    args = arg_strings[start:stop]

-                    action_tuples.append((action, args, option_string))

-                    break

-

-            # add the Optional to the list and return the index at which

-            # the Optional's string args stopped

-            assert action_tuples

-            for action, args, option_string in action_tuples:

-                take_action(action, args, option_string)

-            return stop

-

-        # the list of Positionals left to be parsed; this is modified

-        # by consume_positionals()

-        positionals = self._get_positional_actions()

-

-        # function to convert arg_strings into positional actions

-        def consume_positionals(start_index):

-            # match as many Positionals as possible

-            match_partial = self._match_arguments_partial

-            selected_pattern = arg_strings_pattern[start_index:]

-            arg_counts = match_partial(positionals, selected_pattern)

-

-            # slice off the appropriate arg strings for each Positional

-            # and add the Positional and its args to the list

-            for action, arg_count in zip(positionals, arg_counts):

-                args = arg_strings[start_index: start_index + arg_count]

-                start_index += arg_count

-                take_action(action, args)

-

-            # slice off the Positionals that we just parsed and return the

-            # index at which the Positionals' string args stopped

-            positionals[:] = positionals[len(arg_counts):]

-            return start_index

-

-        # consume Positionals and Optionals alternately, until we have

-        # passed the last option string

-        extras = []

-        start_index = 0

-        if option_string_indices:

-            max_option_string_index = max(option_string_indices)

-        else:

-            max_option_string_index = -1

-        while start_index <= max_option_string_index:

-

-            # consume any Positionals preceding the next option

-            next_option_string_index = min([

-                index

-                for index in option_string_indices

-                if index >= start_index])

-            if start_index != next_option_string_index:

-                positionals_end_index = consume_positionals(start_index)

-

-                # only try to parse the next optional if we didn't consume

-                # the option string during the positionals parsing

-                if positionals_end_index > start_index:

-                    start_index = positionals_end_index

-                    continue

-                else:

-                    start_index = positionals_end_index

-

-            # if we consumed all the positionals we could and we're not

-            # at the index of an option string, there were extra arguments

-            if start_index not in option_string_indices:

-                strings = arg_strings[start_index:next_option_string_index]

-                extras.extend(strings)

-                start_index = next_option_string_index

-

-            # consume the next optional and any arguments for it

-            start_index = consume_optional(start_index)

-

-        # consume any positionals following the last Optional

-        stop_index = consume_positionals(start_index)

-

-        # if we didn't consume all the argument strings, there were extras

-        extras.extend(arg_strings[stop_index:])

-

-        # if we didn't use all the Positional objects, there were too few

-        # arg strings supplied.

-        if positionals:

-            self.error(_('too few arguments'))

-

-        # make sure all required actions were present

-        for action in self._actions:

-            if action.required:

-                if action not in seen_actions:

-                    name = _get_action_name(action)

-                    self.error(_('argument %s is required') % name)

-

-        # make sure all required groups had one option present

-        for group in self._mutually_exclusive_groups:

-            if group.required:

-                for action in group._group_actions:

-                    if action in seen_non_default_actions:

-                        break

-

-                # if no actions were used, report the error

-                else:

-                    names = [_get_action_name(action)

-                             for action in group._group_actions

-                             if action.help is not SUPPRESS]

-                    msg = _('one of the arguments %s is required')

-                    self.error(msg % ' '.join(names))

-

-        # return the updated namespace and the extra arguments

-        return namespace, extras

-

-    def _read_args_from_files(self, arg_strings):

-        # expand arguments referencing files

-        new_arg_strings = []

-        for arg_string in arg_strings:

-

-            # for regular arguments, just add them back into the list

-            if arg_string[0] not in self.fromfile_prefix_chars:

-                new_arg_strings.append(arg_string)

-

-            # replace arguments referencing files with the file content

-            else:

-                try:

-                    args_file = open(arg_string[1:])

-                    try:

-                        arg_strings = []

-                        for arg_line in args_file.read().splitlines():

-                            for arg in self.convert_arg_line_to_args(arg_line):

-                                arg_strings.append(arg)

-                        arg_strings = self._read_args_from_files(arg_strings)

-                        new_arg_strings.extend(arg_strings)

-                    finally:

-                        args_file.close()

-                except IOError:

-                    err = _sys.exc_info()[1]

-                    self.error(str(err))

-

-        # return the modified argument list

-        return new_arg_strings

-

-    def convert_arg_line_to_args(self, arg_line):

-        return [arg_line]

-

-    def _match_argument(self, action, arg_strings_pattern):

-        # match the pattern for this action to the arg strings

-        nargs_pattern = self._get_nargs_pattern(action)

-        match = _re.match(nargs_pattern, arg_strings_pattern)

-

-        # raise an exception if we weren't able to find a match

-        if match is None:

-            nargs_errors = {

-                None: _('expected one argument'),

-                OPTIONAL: _('expected at most one argument'),

-                ONE_OR_MORE: _('expected at least one argument'),

-            }

-            default = _('expected %s argument(s)') % action.nargs

-            msg = nargs_errors.get(action.nargs, default)

-            raise ArgumentError(action, msg)

-

-        # return the number of arguments matched

-        return len(match.group(1))

-

-    def _match_arguments_partial(self, actions, arg_strings_pattern):

-        # progressively shorten the actions list by slicing off the

-        # final actions until we find a match

-        result = []

-        for i in range(len(actions), 0, -1):

-            actions_slice = actions[:i]

-            pattern = ''.join([self._get_nargs_pattern(action)

-                               for action in actions_slice])

-            match = _re.match(pattern, arg_strings_pattern)

-            if match is not None:

-                result.extend([len(string) for string in match.groups()])

-                break

-

-        # return the list of arg string counts

-        return result

-

-    def _parse_optional(self, arg_string):

-        # if it's an empty string, it was meant to be a positional

-        if not arg_string:

-            return None

-

-        # if it doesn't start with a prefix, it was meant to be positional

-        if not arg_string[0] in self.prefix_chars:

-            return None

-

-        # if the option string is present in the parser, return the action

-        if arg_string in self._option_string_actions:

-            action = self._option_string_actions[arg_string]

-            return action, arg_string, None

-

-        # if it's just a single character, it was meant to be positional

-        if len(arg_string) == 1:

-            return None

-

-        # if the option string before the "=" is present, return the action

-        if '=' in arg_string:

-            option_string, explicit_arg = arg_string.split('=', 1)

-            if option_string in self._option_string_actions:

-                action = self._option_string_actions[option_string]

-                return action, option_string, explicit_arg

-

-        # search through all possible prefixes of the option string

-        # and all actions in the parser for possible interpretations

-        option_tuples = self._get_option_tuples(arg_string)

-

-        # if multiple actions match, the option string was ambiguous

-        if len(option_tuples) > 1:

-            options = ', '.join([option_string

-                for action, option_string, explicit_arg in option_tuples])

-            tup = arg_string, options

-            self.error(_('ambiguous option: %s could match %s') % tup)

-

-        # if exactly one action matched, this segmentation is good,

-        # so return the parsed action

-        elif len(option_tuples) == 1:

-            option_tuple, = option_tuples

-            return option_tuple

-

-        # if it was not found as an option, but it looks like a negative

-        # number, it was meant to be positional

-        # unless there are negative-number-like options

-        if self._negative_number_matcher.match(arg_string):

-            if not self._has_negative_number_optionals:

-                return None

-

-        # if it contains a space, it was meant to be a positional

-        if ' ' in arg_string:

-            return None

-

-        # it was meant to be an optional but there is no such option

-        # in this parser (though it might be a valid option in a subparser)

-        return None, arg_string, None

-

-    def _get_option_tuples(self, option_string):

-        result = []

-

-        # option strings starting with two prefix characters are only

-        # split at the '='

-        chars = self.prefix_chars

-        if option_string[0] in chars and option_string[1] in chars:

-            if '=' in option_string:

-                option_prefix, explicit_arg = option_string.split('=', 1)

-            else:

-                option_prefix = option_string

-                explicit_arg = None

-            for option_string in self._option_string_actions:

-                if option_string.startswith(option_prefix):

-                    action = self._option_string_actions[option_string]

-                    tup = action, option_string, explicit_arg

-                    result.append(tup)

-

-        # single character options can be concatenated with their arguments

-        # but multiple character options always have to have their argument

-        # separate

-        elif option_string[0] in chars and option_string[1] not in chars:

-            option_prefix = option_string

-            explicit_arg = None

-            short_option_prefix = option_string[:2]

-            short_explicit_arg = option_string[2:]

-

-            for option_string in self._option_string_actions:

-                if option_string == short_option_prefix:

-                    action = self._option_string_actions[option_string]

-                    tup = action, option_string, short_explicit_arg

-                    result.append(tup)

-                elif option_string.startswith(option_prefix):

-                    action = self._option_string_actions[option_string]

-                    tup = action, option_string, explicit_arg

-                    result.append(tup)

-

-        # shouldn't ever get here

-        else:

-            self.error(_('unexpected option string: %s') % option_string)

-

-        # return the collected option tuples

-        return result

-

-    def _get_nargs_pattern(self, action):

-        # in all examples below, we have to allow for '--' args

-        # which are represented as '-' in the pattern

-        nargs = action.nargs

-

-        # the default (None) is assumed to be a single argument

-        if nargs is None:

-            nargs_pattern = '(-*A-*)'

-

-        # allow zero or one arguments

-        elif nargs == OPTIONAL:

-            nargs_pattern = '(-*A?-*)'

-

-        # allow zero or more arguments

-        elif nargs == ZERO_OR_MORE:

-            nargs_pattern = '(-*[A-]*)'

-

-        # allow one or more arguments

-        elif nargs == ONE_OR_MORE:

-            nargs_pattern = '(-*A[A-]*)'

-

-        # allow any number of options or arguments

-        elif nargs == REMAINDER:

-            nargs_pattern = '([-AO]*)'

-

-        # allow one argument followed by any number of options or arguments

-        elif nargs == PARSER:

-            nargs_pattern = '(-*A[-AO]*)'

-

-        # all others should be integers

-        else:

-            nargs_pattern = '(-*%s-*)' % '-*'.join('A' * nargs)

-

-        # if this is an optional action, -- is not allowed

-        if action.option_strings:

-            nargs_pattern = nargs_pattern.replace('-*', '')

-            nargs_pattern = nargs_pattern.replace('-', '')

-

-        # return the pattern

-        return nargs_pattern

-

-    # ========================

-    # Value conversion methods

-    # ========================

-    def _get_values(self, action, arg_strings):

-        # for everything but PARSER args, strip out '--'

-        if action.nargs not in [PARSER, REMAINDER]:

-            arg_strings = [s for s in arg_strings if s != '--']

-

-        # optional argument produces a default when not present

-        if not arg_strings and action.nargs == OPTIONAL:

-            if action.option_strings:

-                value = action.const

-            else:

-                value = action.default

-            if isinstance(value, _basestring):

-                value = self._get_value(action, value)

-                self._check_value(action, value)

-

-        # when nargs='*' on a positional, if there were no command-line

-        # args, use the default if it is anything other than None

-        elif (not arg_strings and action.nargs == ZERO_OR_MORE and

-              not action.option_strings):

-            if action.default is not None:

-                value = action.default

-            else:

-                value = arg_strings

-            self._check_value(action, value)

-

-        # single argument or optional argument produces a single value

-        elif len(arg_strings) == 1 and action.nargs in [None, OPTIONAL]:

-            arg_string, = arg_strings

-            value = self._get_value(action, arg_string)

-            self._check_value(action, value)

-

-        # REMAINDER arguments convert all values, checking none

-        elif action.nargs == REMAINDER:

-            value = [self._get_value(action, v) for v in arg_strings]

-

-        # PARSER arguments convert all values, but check only the first

-        elif action.nargs == PARSER:

-            value = [self._get_value(action, v) for v in arg_strings]

-            self._check_value(action, value[0])

-

-        # all other types of nargs produce a list

-        else:

-            value = [self._get_value(action, v) for v in arg_strings]

-            for v in value:

-                self._check_value(action, v)

-

-        # return the converted value

-        return value

-

-    def _get_value(self, action, arg_string):

-        type_func = self._registry_get('type', action.type, action.type)

-        if not _callable(type_func):

-            msg = _('%r is not callable')

-            raise ArgumentError(action, msg % type_func)

-

-        # convert the value to the appropriate type

-        try:

-            result = type_func(arg_string)

-

-        # ArgumentTypeErrors indicate errors

-        except ArgumentTypeError:

-            name = getattr(action.type, '__name__', repr(action.type))

-            msg = str(_sys.exc_info()[1])

-            raise ArgumentError(action, msg)

-

-        # TypeErrors or ValueErrors also indicate errors

-        except (TypeError, ValueError):

-            name = getattr(action.type, '__name__', repr(action.type))

-            msg = _('invalid %s value: %r')

-            raise ArgumentError(action, msg % (name, arg_string))

-

-        # return the converted value

-        return result

-

-    def _check_value(self, action, value):

-        # converted value must be one of the choices (if specified)

-        if action.choices is not None and value not in action.choices:

-            tup = value, ', '.join(map(repr, action.choices))

-            msg = _('invalid choice: %r (choose from %s)') % tup

-            raise ArgumentError(action, msg)

-

-    # =======================

-    # Help-formatting methods

-    # =======================

-    def format_usage(self):

-        formatter = self._get_formatter()

-        formatter.add_usage(self.usage, self._actions,

-                            self._mutually_exclusive_groups)

-        return formatter.format_help()

-

-    def format_help(self):

-        formatter = self._get_formatter()

-

-        # usage

-        formatter.add_usage(self.usage, self._actions,

-                            self._mutually_exclusive_groups)

-

-        # description

-        formatter.add_text(self.description)

-

-        # positionals, optionals and user-defined groups

-        for action_group in self._action_groups:

-            formatter.start_section(action_group.title)

-            formatter.add_text(action_group.description)

-            formatter.add_arguments(action_group._group_actions)

-            formatter.end_section()

-

-        # epilog

-        formatter.add_text(self.epilog)

-

-        # determine help from format above

-        return formatter.format_help()

-

-    def format_version(self):

-        import warnings

-        warnings.warn(

-            'The format_version method is deprecated -- the "version" '

-            'argument to ArgumentParser is no longer supported.',

-            DeprecationWarning)

-        formatter = self._get_formatter()

-        formatter.add_text(self.version)

-        return formatter.format_help()

-

-    def _get_formatter(self):

-        return self.formatter_class(prog=self.prog)

-

-    # =====================

-    # Help-printing methods

-    # =====================

-    def print_usage(self, file=None):

-        if file is None:

-            file = _sys.stdout

-        self._print_message(self.format_usage(), file)

-

-    def print_help(self, file=None):

-        if file is None:

-            file = _sys.stdout

-        self._print_message(self.format_help(), file)

-

-    def print_version(self, file=None):

-        import warnings

-        warnings.warn(

-            'The print_version method is deprecated -- the "version" '

-            'argument to ArgumentParser is no longer supported.',

-            DeprecationWarning)

-        self._print_message(self.format_version(), file)

-

-    def _print_message(self, message, file=None):

-        if message:

-            if file is None:

-                file = _sys.stderr

-            file.write(message)

-

-    # ===============

-    # Exiting methods

-    # ===============

-    def exit(self, status=0, message=None):

-        if message:

-            self._print_message(message, _sys.stderr)

-        _sys.exit(status)

-

-    def error(self, message):

-        """error(message: string)

-

-        Prints a usage message incorporating the message to stderr and

-        exits.

-

-        If you override this in a subclass, it should not return -- it

-        should either exit or raise an exception.

-        """

-        self.print_usage(_sys.stderr)

-        self.exit(2, _('%s: error: %s\n') % (self.prog, message))

+# Copyright 2006-2009 Steven J. Bethard <steven.bethard@gmail.com>.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy
+# of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+"""Command-line parsing library
+
+This module is an optparse-inspired command-line parsing library that:
+
+    - handles both optional and positional arguments
+    - produces highly informative usage messages
+    - supports parsers that dispatch to sub-parsers
+
+The following is a simple usage example that sums integers from the
+command-line and writes the result to a file::
+
+    parser = argparse.ArgumentParser(
+        description='sum the integers at the command line')
+    parser.add_argument(
+        'integers', metavar='int', nargs='+', type=int,
+        help='an integer to be summed')
+    parser.add_argument(
+        '--log', default=sys.stdout, type=argparse.FileType('w'),
+        help='the file where the sum should be written')
+    args = parser.parse_args()
+    args.log.write('%s' % sum(args.integers))
+    args.log.close()
+
+The module contains the following public classes:
+
+    - ArgumentParser -- The main entry point for command-line parsing. As the
+        example above shows, the add_argument() method is used to populate
+        the parser with actions for optional and positional arguments. Then
+        the parse_args() method is invoked to convert the args at the
+        command-line into an object with attributes.
+
+    - ArgumentError -- The exception raised by ArgumentParser objects when
+        there are errors with the parser's actions. Errors raised while
+        parsing the command-line are caught by ArgumentParser and emitted
+        as command-line messages.
+
+    - FileType -- A factory for defining types of files to be created. As the
+        example above shows, instances of FileType are typically passed as
+        the type= argument of add_argument() calls.
+
+    - Action -- The base class for parser actions. Typically actions are
+        selected by passing strings like 'store_true' or 'append_const' to
+        the action= argument of add_argument(). However, for greater
+        customization of ArgumentParser actions, subclasses of Action may
+        be defined and passed as the action= argument.
+
+    - HelpFormatter, RawDescriptionHelpFormatter, RawTextHelpFormatter,
+        ArgumentDefaultsHelpFormatter -- Formatter classes which
+        may be passed as the formatter_class= argument to the
+        ArgumentParser constructor. HelpFormatter is the default,
+        RawDescriptionHelpFormatter and RawTextHelpFormatter tell the parser
+        not to change the formatting for help text, and
+        ArgumentDefaultsHelpFormatter adds information about argument defaults
+        to the help.
+
+All other classes in this module are considered implementation details.
+(Also note that HelpFormatter and RawDescriptionHelpFormatter are only
+considered public as object names -- the API of the formatter objects is
+still considered an implementation detail.)
+"""
+
+__version__ = '1.1'
+__all__ = [
+    'ArgumentParser',
+    'ArgumentError',
+    'Namespace',
+    'Action',
+    'FileType',
+    'HelpFormatter',
+    'RawDescriptionHelpFormatter',
+    'RawTextHelpFormatter',
+    'ArgumentDefaultsHelpFormatter',
+]
+
+
+import copy as _copy
+import os as _os
+import re as _re
+import sys as _sys
+import textwrap as _textwrap
+
+from gettext import gettext as _
+
+try:
+    _set = set
+except NameError:
+    from sets import Set as _set
+
+try:
+    _basestring = basestring
+except NameError:
+    _basestring = str
+
+try:
+    _sorted = sorted
+except NameError:
+
+    def _sorted(iterable, reverse=False):
+        result = list(iterable)
+        result.sort()
+        if reverse:
+            result.reverse()
+        return result
+
+
+def _callable(obj):
+    return hasattr(obj, '__call__') or hasattr(obj, '__bases__')
+
+# silence Python 2.6 buggy warnings about Exception.message
+if _sys.version_info[:2] == (2, 6):
+    import warnings
+    warnings.filterwarnings(
+        action='ignore',
+        message='BaseException.message has been deprecated as of Python 2.6',
+        category=DeprecationWarning,
+        module='argparse')
+
+
+SUPPRESS = '==SUPPRESS=='
+
+OPTIONAL = '?'
+ZERO_OR_MORE = '*'
+ONE_OR_MORE = '+'
+PARSER = 'A...'
+REMAINDER = '...'
+
+# =============================
+# Utility functions and classes
+# =============================
+
+class _AttributeHolder(object):
+    """Abstract base class that provides __repr__.
+
+    The __repr__ method returns a string in the format::
+        ClassName(attr=name, attr=name, ...)
+    The attributes are determined either by a class-level attribute,
+    '_kwarg_names', or by inspecting the instance __dict__.
+    """
+
+    def __repr__(self):
+        type_name = type(self).__name__
+        arg_strings = []
+        for arg in self._get_args():
+            arg_strings.append(repr(arg))
+        for name, value in self._get_kwargs():
+            arg_strings.append('%s=%r' % (name, value))
+        return '%s(%s)' % (type_name, ', '.join(arg_strings))
+
+    def _get_kwargs(self):
+        return _sorted(self.__dict__.items())
+
+    def _get_args(self):
+        return []
+
+
+def _ensure_value(namespace, name, value):
+    if getattr(namespace, name, None) is None:
+        setattr(namespace, name, value)
+    return getattr(namespace, name)
+
+
+# ===============
+# Formatting Help
+# ===============
+
+class HelpFormatter(object):
+    """Formatter for generating usage messages and argument help strings.
+
+    Only the name of this class is considered a public API. All the methods
+    provided by the class are considered an implementation detail.
+    """
+
+    def __init__(self,
+                 prog,
+                 indent_increment=2,
+                 max_help_position=24,
+                 width=None):
+
+        # default setting for width
+        if width is None:
+            try:
+                width = int(_os.environ['COLUMNS'])
+            except (KeyError, ValueError):
+                width = 80
+            width -= 2
+
+        self._prog = prog
+        self._indent_increment = indent_increment
+        self._max_help_position = max_help_position
+        self._width = width
+
+        self._current_indent = 0
+        self._level = 0
+        self._action_max_length = 0
+
+        self._root_section = self._Section(self, None)
+        self._current_section = self._root_section
+
+        self._whitespace_matcher = _re.compile(r'\s+')
+        self._long_break_matcher = _re.compile(r'\n\n\n+')
+
+    # ===============================
+    # Section and indentation methods
+    # ===============================
+    def _indent(self):
+        self._current_indent += self._indent_increment
+        self._level += 1
+
+    def _dedent(self):
+        self._current_indent -= self._indent_increment
+        assert self._current_indent >= 0, 'Indent decreased below 0.'
+        self._level -= 1
+
+    class _Section(object):
+
+        def __init__(self, formatter, parent, heading=None):
+            self.formatter = formatter
+            self.parent = parent
+            self.heading = heading
+            self.items = []
+
+        def format_help(self):
+            # format the indented section
+            if self.parent is not None:
+                self.formatter._indent()
+            join = self.formatter._join_parts
+            for func, args in self.items:
+                func(*args)
+            item_help = join([func(*args) for func, args in self.items])
+            if self.parent is not None:
+                self.formatter._dedent()
+
+            # return nothing if the section was empty
+            if not item_help:
+                return ''
+
+            # add the heading if the section was non-empty
+            if self.heading is not SUPPRESS and self.heading is not None:
+                current_indent = self.formatter._current_indent
+                heading = '%*s%s:\n' % (current_indent, '', self.heading)
+            else:
+                heading = ''
+
+            # join the section-initial newline, the heading and the help
+            return join(['\n', heading, item_help, '\n'])
+
+    def _add_item(self, func, args):
+        self._current_section.items.append((func, args))
+
+    # ========================
+    # Message building methods
+    # ========================
+    def start_section(self, heading):
+        self._indent()
+        section = self._Section(self, self._current_section, heading)
+        self._add_item(section.format_help, [])
+        self._current_section = section
+
+    def end_section(self):
+        self._current_section = self._current_section.parent
+        self._dedent()
+
+    def add_text(self, text):
+        if text is not SUPPRESS and text is not None:
+            self._add_item(self._format_text, [text])
+
+    def add_usage(self, usage, actions, groups, prefix=None):
+        if usage is not SUPPRESS:
+            args = usage, actions, groups, prefix
+            self._add_item(self._format_usage, args)
+
+    def add_argument(self, action):
+        if action.help is not SUPPRESS:
+
+            # find all invocations
+            get_invocation = self._format_action_invocation
+            invocations = [get_invocation(action)]
+            for subaction in self._iter_indented_subactions(action):
+                invocations.append(get_invocation(subaction))
+
+            # update the maximum item length
+            invocation_length = max([len(s) for s in invocations])
+            action_length = invocation_length + self._current_indent
+            self._action_max_length = max(self._action_max_length,
+                                          action_length)
+
+            # add the item to the list
+            self._add_item(self._format_action, [action])
+
+    def add_arguments(self, actions):
+        for action in actions:
+            self.add_argument(action)
+
+    # =======================
+    # Help-formatting methods
+    # =======================
+    def format_help(self):
+        help = self._root_section.format_help()
+        if help:
+            help = self._long_break_matcher.sub('\n\n', help)
+            help = help.strip('\n') + '\n'
+        return help
+
+    def _join_parts(self, part_strings):
+        return ''.join([part
+                        for part in part_strings
+                        if part and part is not SUPPRESS])
+
+    def _format_usage(self, usage, actions, groups, prefix):
+        if prefix is None:
+            prefix = _('usage: ')
+
+        # if usage is specified, use that
+        if usage is not None:
+            usage = usage % dict(prog=self._prog)
+
+        # if no optionals or positionals are available, usage is just prog
+        elif usage is None and not actions:
+            usage = '%(prog)s' % dict(prog=self._prog)
+
+        # if optionals and positionals are available, calculate usage
+        elif usage is None:
+            prog = '%(prog)s' % dict(prog=self._prog)
+
+            # split optionals from positionals
+            optionals = []
+            positionals = []
+            for action in actions:
+                if action.option_strings:
+                    optionals.append(action)
+                else:
+                    positionals.append(action)
+
+            # build full usage string
+            format = self._format_actions_usage
+            action_usage = format(optionals + positionals, groups)
+            usage = ' '.join([s for s in [prog, action_usage] if s])
+
+            # wrap the usage parts if it's too long
+            text_width = self._width - self._current_indent
+            if len(prefix) + len(usage) > text_width:
+
+                # break usage into wrappable parts
+                part_regexp = r'\(.*?\)+|\[.*?\]+|\S+'
+                opt_usage = format(optionals, groups)
+                pos_usage = format(positionals, groups)
+                opt_parts = _re.findall(part_regexp, opt_usage)
+                pos_parts = _re.findall(part_regexp, pos_usage)
+                assert ' '.join(opt_parts) == opt_usage
+                assert ' '.join(pos_parts) == pos_usage
+
+                # helper for wrapping lines
+                def get_lines(parts, indent, prefix=None):
+                    lines = []
+                    line = []
+                    if prefix is not None:
+                        line_len = len(prefix) - 1
+                    else:
+                        line_len = len(indent) - 1
+                    for part in parts:
+                        if line_len + 1 + len(part) > text_width:
+                            lines.append(indent + ' '.join(line))
+                            line = []
+                            line_len = len(indent) - 1
+                        line.append(part)
+                        line_len += len(part) + 1
+                    if line:
+                        lines.append(indent + ' '.join(line))
+                    if prefix is not None:
+                        lines[0] = lines[0][len(indent):]
+                    return lines
+
+                # if prog is short, follow it with optionals or positionals
+                if len(prefix) + len(prog) <= 0.75 * text_width:
+                    indent = ' ' * (len(prefix) + len(prog) + 1)
+                    if opt_parts:
+                        lines = get_lines([prog] + opt_parts, indent, prefix)
+                        lines.extend(get_lines(pos_parts, indent))
+                    elif pos_parts:
+                        lines = get_lines([prog] + pos_parts, indent, prefix)
+                    else:
+                        lines = [prog]
+
+                # if prog is long, put it on its own line
+                else:
+                    indent = ' ' * len(prefix)
+                    parts = opt_parts + pos_parts
+                    lines = get_lines(parts, indent)
+                    if len(lines) > 1:
+                        lines = []
+                        lines.extend(get_lines(opt_parts, indent))
+                        lines.extend(get_lines(pos_parts, indent))
+                    lines = [prog] + lines
+
+                # join lines into usage
+                usage = '\n'.join(lines)
+
+        # prefix with 'usage:'
+        return '%s%s\n\n' % (prefix, usage)
+
+    def _format_actions_usage(self, actions, groups):
+        # find group indices and identify actions in groups
+        group_actions = _set()
+        inserts = {}
+        for group in groups:
+            try:
+                start = actions.index(group._group_actions[0])
+            except ValueError:
+                continue
+            else:
+                end = start + len(group._group_actions)
+                if actions[start:end] == group._group_actions:
+                    for action in group._group_actions:
+                        group_actions.add(action)
+                    if not group.required:
+                        inserts[start] = '['
+                        inserts[end] = ']'
+                    else:
+                        inserts[start] = '('
+                        inserts[end] = ')'
+                    for i in range(start + 1, end):
+                        inserts[i] = '|'
+
+        # collect all actions format strings
+        parts = []
+        for i, action in enumerate(actions):
+
+            # suppressed arguments are marked with None
+            # remove | separators for suppressed arguments
+            if action.help is SUPPRESS:
+                parts.append(None)
+                if inserts.get(i) == '|':
+                    inserts.pop(i)
+                elif inserts.get(i + 1) == '|':
+                    inserts.pop(i + 1)
+
+            # produce all arg strings
+            elif not action.option_strings:
+                part = self._format_args(action, action.dest)
+
+                # if it's in a group, strip the outer []
+                if action in group_actions:
+                    if part[0] == '[' and part[-1] == ']':
+                        part = part[1:-1]
+
+                # add the action string to the list
+                parts.append(part)
+
+            # produce the first way to invoke the option in brackets
+            else:
+                option_string = action.option_strings[0]
+
+                # if the Optional doesn't take a value, format is:
+                #    -s or --long
+                if action.nargs == 0:
+                    part = '%s' % option_string
+
+                # if the Optional takes a value, format is:
+                #    -s ARGS or --long ARGS
+                else:
+                    default = action.dest.upper()
+                    args_string = self._format_args(action, default)
+                    part = '%s %s' % (option_string, args_string)
+
+                # make it look optional if it's not required or in a group
+                if not action.required and action not in group_actions:
+                    part = '[%s]' % part
+
+                # add the action string to the list
+                parts.append(part)
+
+        # insert things at the necessary indices
+        for i in _sorted(inserts, reverse=True):
+            parts[i:i] = [inserts[i]]
+
+        # join all the action items with spaces
+        text = ' '.join([item for item in parts if item is not None])
+
+        # clean up separators for mutually exclusive groups
+        open = r'[\[(]'
+        close = r'[\])]'
+        text = _re.sub(r'(%s) ' % open, r'\1', text)
+        text = _re.sub(r' (%s)' % close, r'\1', text)
+        text = _re.sub(r'%s *%s' % (open, close), r'', text)
+        text = _re.sub(r'\(([^|]*)\)', r'\1', text)
+        text = text.strip()
+
+        # return the text
+        return text
+
+    def _format_text(self, text):
+        if '%(prog)' in text:
+            text = text % dict(prog=self._prog)
+        text_width = self._width - self._current_indent
+        indent = ' ' * self._current_indent
+        return self._fill_text(text, text_width, indent) + '\n\n'
+
+    def _format_action(self, action):
+        # determine the required width and the entry label
+        help_position = min(self._action_max_length + 2,
+                            self._max_help_position)
+        help_width = self._width - help_position
+        action_width = help_position - self._current_indent - 2
+        action_header = self._format_action_invocation(action)
+
+        # ho nelp; start on same line and add a final newline
+        if not action.help:
+            tup = self._current_indent, '', action_header
+            action_header = '%*s%s\n' % tup
+
+        # short action name; start on the same line and pad two spaces
+        elif len(action_header) <= action_width:
+            tup = self._current_indent, '', action_width, action_header
+            action_header = '%*s%-*s  ' % tup
+            indent_first = 0
+
+        # long action name; start on the next line
+        else:
+            tup = self._current_indent, '', action_header
+            action_header = '%*s%s\n' % tup
+            indent_first = help_position
+
+        # collect the pieces of the action help
+        parts = [action_header]
+
+        # if there was help for the action, add lines of help text
+        if action.help:
+            help_text = self._expand_help(action)
+            help_lines = self._split_lines(help_text, help_width)
+            parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))
+            for line in help_lines[1:]:
+                parts.append('%*s%s\n' % (help_position, '', line))
+
+        # or add a newline if the description doesn't end with one
+        elif not action_header.endswith('\n'):
+            parts.append('\n')
+
+        # if there are any sub-actions, add their help as well
+        for subaction in self._iter_indented_subactions(action):
+            parts.append(self._format_action(subaction))
+
+        # return a single string
+        return self._join_parts(parts)
+
+    def _format_action_invocation(self, action):
+        if not action.option_strings:
+            metavar, = self._metavar_formatter(action, action.dest)(1)
+            return metavar
+
+        else:
+            parts = []
+
+            # if the Optional doesn't take a value, format is:
+            #    -s, --long
+            if action.nargs == 0:
+                parts.extend(action.option_strings)
+
+            # if the Optional takes a value, format is:
+            #    -s ARGS, --long ARGS
+            else:
+                default = action.dest.upper()
+                args_string = self._format_args(action, default)
+                for option_string in action.option_strings:
+                    parts.append('%s %s' % (option_string, args_string))
+
+            return ', '.join(parts)
+
+    def _metavar_formatter(self, action, default_metavar):
+        if action.metavar is not None:
+            result = action.metavar
+        elif action.choices is not None:
+            choice_strs = [str(choice) for choice in action.choices]
+            result = '{%s}' % ','.join(choice_strs)
+        else:
+            result = default_metavar
+
+        def format(tuple_size):
+            if isinstance(result, tuple):
+                return result
+            else:
+                return (result, ) * tuple_size
+        return format
+
+    def _format_args(self, action, default_metavar):
+        get_metavar = self._metavar_formatter(action, default_metavar)
+        if action.nargs is None:
+            result = '%s' % get_metavar(1)
+        elif action.nargs == OPTIONAL:
+            result = '[%s]' % get_metavar(1)
+        elif action.nargs == ZERO_OR_MORE:
+            result = '[%s [%s ...]]' % get_metavar(2)
+        elif action.nargs == ONE_OR_MORE:
+            result = '%s [%s ...]' % get_metavar(2)
+        elif action.nargs == REMAINDER:
+            result = '...'
+        elif action.nargs == PARSER:
+            result = '%s ...' % get_metavar(1)
+        else:
+            formats = ['%s' for _ in range(action.nargs)]
+            result = ' '.join(formats) % get_metavar(action.nargs)
+        return result
+
+    def _expand_help(self, action):
+        params = dict(vars(action), prog=self._prog)
+        for name in list(params):
+            if params[name] is SUPPRESS:
+                del params[name]
+        for name in list(params):
+            if hasattr(params[name], '__name__'):
+                params[name] = params[name].__name__
+        if params.get('choices') is not None:
+            choices_str = ', '.join([str(c) for c in params['choices']])
+            params['choices'] = choices_str
+        return self._get_help_string(action) % params
+
+    def _iter_indented_subactions(self, action):
+        try:
+            get_subactions = action._get_subactions
+        except AttributeError:
+            pass
+        else:
+            self._indent()
+            for subaction in get_subactions():
+                yield subaction
+            self._dedent()
+
+    def _split_lines(self, text, width):
+        text = self._whitespace_matcher.sub(' ', text).strip()
+        return _textwrap.wrap(text, width)
+
+    def _fill_text(self, text, width, indent):
+        text = self._whitespace_matcher.sub(' ', text).strip()
+        return _textwrap.fill(text, width, initial_indent=indent,
+                                           subsequent_indent=indent)
+
+    def _get_help_string(self, action):
+        return action.help
+
+
+class RawDescriptionHelpFormatter(HelpFormatter):
+    """Help message formatter which retains any formatting in descriptions.
+
+    Only the name of this class is considered a public API. All the methods
+    provided by the class are considered an implementation detail.
+    """
+
+    def _fill_text(self, text, width, indent):
+        return ''.join([indent + line for line in text.splitlines(True)])
+
+
+class RawTextHelpFormatter(RawDescriptionHelpFormatter):
+    """Help message formatter which retains formatting of all help text.
+
+    Only the name of this class is considered a public API. All the methods
+    provided by the class are considered an implementation detail.
+    """
+
+    def _split_lines(self, text, width):
+        return text.splitlines()
+
+
+class ArgumentDefaultsHelpFormatter(HelpFormatter):
+    """Help message formatter which adds default values to argument help.
+
+    Only the name of this class is considered a public API. All the methods
+    provided by the class are considered an implementation detail.
+    """
+
+    def _get_help_string(self, action):
+        help = action.help
+        if '%(default)' not in action.help:
+            if action.default is not SUPPRESS:
+                defaulting_nargs = [OPTIONAL, ZERO_OR_MORE]
+                if action.option_strings or action.nargs in defaulting_nargs:
+                    help += ' (default: %(default)s)'
+        return help
+
+
+# =====================
+# Options and Arguments
+# =====================
+
+def _get_action_name(argument):
+    if argument is None:
+        return None
+    elif argument.option_strings:
+        return  '/'.join(argument.option_strings)
+    elif argument.metavar not in (None, SUPPRESS):
+        return argument.metavar
+    elif argument.dest not in (None, SUPPRESS):
+        return argument.dest
+    else:
+        return None
+
+
+class ArgumentError(Exception):
+    """An error from creating or using an argument (optional or positional).
+
+    The string value of this exception is the message, augmented with
+    information about the argument that caused it.
+    """
+
+    def __init__(self, argument, message):
+        self.argument_name = _get_action_name(argument)
+        self.message = message
+
+    def __str__(self):
+        if self.argument_name is None:
+            format = '%(message)s'
+        else:
+            format = 'argument %(argument_name)s: %(message)s'
+        return format % dict(message=self.message,
+                             argument_name=self.argument_name)
+
+
+class ArgumentTypeError(Exception):
+    """An error from trying to convert a command line string to a type."""
+    pass
+
+
+# ==============
+# Action classes
+# ==============
+
+class Action(_AttributeHolder):
+    """Information about how to convert command line strings to Python objects.
+
+    Action objects are used by an ArgumentParser to represent the information
+    needed to parse a single argument from one or more strings from the
+    command line. The keyword arguments to the Action constructor are also
+    all attributes of Action instances.
+
+    Keyword Arguments:
+
+        - option_strings -- A list of command-line option strings which
+            should be associated with this action.
+
+        - dest -- The name of the attribute to hold the created object(s)
+
+        - nargs -- The number of command-line arguments that should be
+            consumed. By default, one argument will be consumed and a single
+            value will be produced.  Other values include:
+                - N (an integer) consumes N arguments (and produces a list)
+                - '?' consumes zero or one arguments
+                - '*' consumes zero or more arguments (and produces a list)
+                - '+' consumes one or more arguments (and produces a list)
+            Note that the difference between the default and nargs=1 is that
+            with the default, a single value will be produced, while with
+            nargs=1, a list containing a single value will be produced.
+
+        - const -- The value to be produced if the option is specified and the
+            option uses an action that takes no values.
+
+        - default -- The value to be produced if the option is not specified.
+
+        - type -- The type which the command-line arguments should be converted
+            to, should be one of 'string', 'int', 'float', 'complex' or a
+            callable object that accepts a single string argument. If None,
+            'string' is assumed.
+
+        - choices -- A container of values that should be allowed. If not None,
+            after a command-line argument has been converted to the appropriate
+            type, an exception will be raised if it is not a member of this
+            collection.
+
+        - required -- True if the action must always be specified at the
+            command line. This is only meaningful for optional command-line
+            arguments.
+
+        - help -- The help string describing the argument.
+
+        - metavar -- The name to be used for the option's argument with the
+            help string. If None, the 'dest' value will be used as the name.
+    """
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 nargs=None,
+                 const=None,
+                 default=None,
+                 type=None,
+                 choices=None,
+                 required=False,
+                 help=None,
+                 metavar=None):
+        self.option_strings = option_strings
+        self.dest = dest
+        self.nargs = nargs
+        self.const = const
+        self.default = default
+        self.type = type
+        self.choices = choices
+        self.required = required
+        self.help = help
+        self.metavar = metavar
+
+    def _get_kwargs(self):
+        names = [
+            'option_strings',
+            'dest',
+            'nargs',
+            'const',
+            'default',
+            'type',
+            'choices',
+            'help',
+            'metavar',
+        ]
+        return [(name, getattr(self, name)) for name in names]
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        raise NotImplementedError(_('.__call__() not defined'))
+
+
+class _StoreAction(Action):
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 nargs=None,
+                 const=None,
+                 default=None,
+                 type=None,
+                 choices=None,
+                 required=False,
+                 help=None,
+                 metavar=None):
+        if nargs == 0:
+            raise ValueError('nargs for store actions must be > 0; if you '
+                             'have nothing to store, actions such as store '
+                             'true or store const may be more appropriate')
+        if const is not None and nargs != OPTIONAL:
+            raise ValueError('nargs must be %r to supply const' % OPTIONAL)
+        super(_StoreAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            nargs=nargs,
+            const=const,
+            default=default,
+            type=type,
+            choices=choices,
+            required=required,
+            help=help,
+            metavar=metavar)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        setattr(namespace, self.dest, values)
+
+
+class _StoreConstAction(Action):
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 const,
+                 default=None,
+                 required=False,
+                 help=None,
+                 metavar=None):
+        super(_StoreConstAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            nargs=0,
+            const=const,
+            default=default,
+            required=required,
+            help=help)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        setattr(namespace, self.dest, self.const)
+
+
+class _StoreTrueAction(_StoreConstAction):
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 default=False,
+                 required=False,
+                 help=None):
+        super(_StoreTrueAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            const=True,
+            default=default,
+            required=required,
+            help=help)
+
+
+class _StoreFalseAction(_StoreConstAction):
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 default=True,
+                 required=False,
+                 help=None):
+        super(_StoreFalseAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            const=False,
+            default=default,
+            required=required,
+            help=help)
+
+
+class _AppendAction(Action):
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 nargs=None,
+                 const=None,
+                 default=None,
+                 type=None,
+                 choices=None,
+                 required=False,
+                 help=None,
+                 metavar=None):
+        if nargs == 0:
+            raise ValueError('nargs for append actions must be > 0; if arg '
+                             'strings are not supplying the value to append, '
+                             'the append const action may be more appropriate')
+        if const is not None and nargs != OPTIONAL:
+            raise ValueError('nargs must be %r to supply const' % OPTIONAL)
+        super(_AppendAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            nargs=nargs,
+            const=const,
+            default=default,
+            type=type,
+            choices=choices,
+            required=required,
+            help=help,
+            metavar=metavar)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = _copy.copy(_ensure_value(namespace, self.dest, []))
+        items.append(values)
+        setattr(namespace, self.dest, items)
+
+
+class _AppendConstAction(Action):
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 const,
+                 default=None,
+                 required=False,
+                 help=None,
+                 metavar=None):
+        super(_AppendConstAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            nargs=0,
+            const=const,
+            default=default,
+            required=required,
+            help=help,
+            metavar=metavar)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = _copy.copy(_ensure_value(namespace, self.dest, []))
+        items.append(self.const)
+        setattr(namespace, self.dest, items)
+
+
+class _CountAction(Action):
+
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 default=None,
+                 required=False,
+                 help=None):
+        super(_CountAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            nargs=0,
+            default=default,
+            required=required,
+            help=help)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        new_count = _ensure_value(namespace, self.dest, 0) + 1
+        setattr(namespace, self.dest, new_count)
+
+
+class _HelpAction(Action):
+
+    def __init__(self,
+                 option_strings,
+                 dest=SUPPRESS,
+                 default=SUPPRESS,
+                 help=None):
+        super(_HelpAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            default=default,
+            nargs=0,
+            help=help)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        parser.print_help()
+        parser.exit()
+
+
+class _VersionAction(Action):
+
+    def __init__(self,
+                 option_strings,
+                 version=None,
+                 dest=SUPPRESS,
+                 default=SUPPRESS,
+                 help=None):
+        super(_VersionAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            default=default,
+            nargs=0,
+            help=help)
+        self.version = version
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        version = self.version
+        if version is None:
+            version = parser.version
+        formatter = parser._get_formatter()
+        formatter.add_text(version)
+        parser.exit(message=formatter.format_help())
+
+
+class _SubParsersAction(Action):
+
+    class _ChoicesPseudoAction(Action):
+
+        def __init__(self, name, help):
+            sup = super(_SubParsersAction._ChoicesPseudoAction, self)
+            sup.__init__(option_strings=[], dest=name, help=help)
+
+    def __init__(self,
+                 option_strings,
+                 prog,
+                 parser_class,
+                 dest=SUPPRESS,
+                 help=None,
+                 metavar=None):
+
+        self._prog_prefix = prog
+        self._parser_class = parser_class
+        self._name_parser_map = {}
+        self._choices_actions = []
+
+        super(_SubParsersAction, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            nargs=PARSER,
+            choices=self._name_parser_map,
+            help=help,
+            metavar=metavar)
+
+    def add_parser(self, name, **kwargs):
+        # set prog from the existing prefix
+        if kwargs.get('prog') is None:
+            kwargs['prog'] = '%s %s' % (self._prog_prefix, name)
+
+        # create a pseudo-action to hold the choice help
+        if 'help' in kwargs:
+            help = kwargs.pop('help')
+            choice_action = self._ChoicesPseudoAction(name, help)
+            self._choices_actions.append(choice_action)
+
+        # create the parser and add it to the map
+        parser = self._parser_class(**kwargs)
+        self._name_parser_map[name] = parser
+        return parser
+
+    def _get_subactions(self):
+        return self._choices_actions
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        parser_name = values[0]
+        arg_strings = values[1:]
+
+        # set the parser name if requested
+        if self.dest is not SUPPRESS:
+            setattr(namespace, self.dest, parser_name)
+
+        # select the parser
+        try:
+            parser = self._name_parser_map[parser_name]
+        except KeyError:
+            tup = parser_name, ', '.join(self._name_parser_map)
+            msg = _('unknown parser %r (choices: %s)' % tup)
+            raise ArgumentError(self, msg)
+
+        # parse all the remaining options into the namespace
+        parser.parse_args(arg_strings, namespace)
+
+
+# ==============
+# Type classes
+# ==============
+
+class FileType(object):
+    """Factory for creating file object types
+
+    Instances of FileType are typically passed as type= arguments to the
+    ArgumentParser add_argument() method.
+
+    Keyword Arguments:
+        - mode -- A string indicating how the file is to be opened. Accepts the
+            same values as the builtin open() function.
+        - bufsize -- The file's desired buffer size. Accepts the same values as
+            the builtin open() function.
+    """
+
+    def __init__(self, mode='r', bufsize=None):
+        self._mode = mode
+        self._bufsize = bufsize
+
+    def __call__(self, string):
+        # the special argument "-" means sys.std{in,out}
+        if string == '-':
+            if 'r' in self._mode:
+                return _sys.stdin
+            elif 'w' in self._mode:
+                return _sys.stdout
+            else:
+                msg = _('argument "-" with mode %r' % self._mode)
+                raise ValueError(msg)
+
+        # all other arguments are used as file names
+        if self._bufsize:
+            return open(string, self._mode, self._bufsize)
+        else:
+            return open(string, self._mode)
+
+    def __repr__(self):
+        args = [self._mode, self._bufsize]
+        args_str = ', '.join([repr(arg) for arg in args if arg is not None])
+        return '%s(%s)' % (type(self).__name__, args_str)
+
+# ===========================
+# Optional and Positional Parsing
+# ===========================
+
+class Namespace(_AttributeHolder):
+    """Simple object for storing attributes.
+
+    Implements equality by attribute names and values, and provides a simple
+    string representation.
+    """
+
+    def __init__(self, **kwargs):
+        for name in kwargs:
+            setattr(self, name, kwargs[name])
+
+    def __eq__(self, other):
+        return vars(self) == vars(other)
+
+    def __ne__(self, other):
+        return not (self == other)
+
+    def __contains__(self, key):
+        return key in self.__dict__
+
+
+class _ActionsContainer(object):
+
+    def __init__(self,
+                 description,
+                 prefix_chars,
+                 argument_default,
+                 conflict_handler):
+        super(_ActionsContainer, self).__init__()
+
+        self.description = description
+        self.argument_default = argument_default
+        self.prefix_chars = prefix_chars
+        self.conflict_handler = conflict_handler
+
+        # set up registries
+        self._registries = {}
+
+        # register actions
+        self.register('action', None, _StoreAction)
+        self.register('action', 'store', _StoreAction)
+        self.register('action', 'store_const', _StoreConstAction)
+        self.register('action', 'store_true', _StoreTrueAction)
+        self.register('action', 'store_false', _StoreFalseAction)
+        self.register('action', 'append', _AppendAction)
+        self.register('action', 'append_const', _AppendConstAction)
+        self.register('action', 'count', _CountAction)
+        self.register('action', 'help', _HelpAction)
+        self.register('action', 'version', _VersionAction)
+        self.register('action', 'parsers', _SubParsersAction)
+
+        # raise an exception if the conflict handler is invalid
+        self._get_handler()
+
+        # action storage
+        self._actions = []
+        self._option_string_actions = {}
+
+        # groups
+        self._action_groups = []
+        self._mutually_exclusive_groups = []
+
+        # defaults storage
+        self._defaults = {}
+
+        # determines whether an "option" looks like a negative number
+        self._negative_number_matcher = _re.compile(r'^-\d+$|^-\d*\.\d+$')
+
+        # whether or not there are any optionals that look like negative
+        # numbers -- uses a list so it can be shared and edited
+        self._has_negative_number_optionals = []
+
+    # ====================
+    # Registration methods
+    # ====================
+    def register(self, registry_name, value, object):
+        registry = self._registries.setdefault(registry_name, {})
+        registry[value] = object
+
+    def _registry_get(self, registry_name, value, default=None):
+        return self._registries[registry_name].get(value, default)
+
+    # ==================================
+    # Namespace default accessor methods
+    # ==================================
+    def set_defaults(self, **kwargs):
+        self._defaults.update(kwargs)
+
+        # if these defaults match any existing arguments, replace
+        # the previous default on the object with the new one
+        for action in self._actions:
+            if action.dest in kwargs:
+                action.default = kwargs[action.dest]
+
+    def get_default(self, dest):
+        for action in self._actions:
+            if action.dest == dest and action.default is not None:
+                return action.default
+        return self._defaults.get(dest, None)
+
+
+    # =======================
+    # Adding argument actions
+    # =======================
+    def add_argument(self, *args, **kwargs):
+        """
+        add_argument(dest, ..., name=value, ...)
+        add_argument(option_string, option_string, ..., name=value, ...)
+        """
+
+        # if no positional args are supplied or only one is supplied and
+        # it doesn't look like an option string, parse a positional
+        # argument
+        chars = self.prefix_chars
+        if not args or len(args) == 1 and args[0][0] not in chars:
+            if args and 'dest' in kwargs:
+                raise ValueError('dest supplied twice for positional argument')
+            kwargs = self._get_positional_kwargs(*args, **kwargs)
+
+        # otherwise, we're adding an optional argument
+        else:
+            kwargs = self._get_optional_kwargs(*args, **kwargs)
+
+        # if no default was supplied, use the parser-level default
+        if 'default' not in kwargs:
+            dest = kwargs['dest']
+            if dest in self._defaults:
+                kwargs['default'] = self._defaults[dest]
+            elif self.argument_default is not None:
+                kwargs['default'] = self.argument_default
+
+        # create the action object, and add it to the parser
+        action_class = self._pop_action_class(kwargs)
+        if not _callable(action_class):
+            raise ValueError('unknown action "%s"' % action_class)
+        action = action_class(**kwargs)
+
+        # raise an error if the action type is not callable
+        type_func = self._registry_get('type', action.type, action.type)
+        if not _callable(type_func):
+            raise ValueError('%r is not callable' % type_func)
+
+        return self._add_action(action)
+
+    def add_argument_group(self, *args, **kwargs):
+        group = _ArgumentGroup(self, *args, **kwargs)
+        self._action_groups.append(group)
+        return group
+
+    def add_mutually_exclusive_group(self, **kwargs):
+        group = _MutuallyExclusiveGroup(self, **kwargs)
+        self._mutually_exclusive_groups.append(group)
+        return group
+
+    def _add_action(self, action):
+        # resolve any conflicts
+        self._check_conflict(action)
+
+        # add to actions list
+        self._actions.append(action)
+        action.container = self
+
+        # index the action by any option strings it has
+        for option_string in action.option_strings:
+            self._option_string_actions[option_string] = action
+
+        # set the flag if any option strings look like negative numbers
+        for option_string in action.option_strings:
+            if self._negative_number_matcher.match(option_string):
+                if not self._has_negative_number_optionals:
+                    self._has_negative_number_optionals.append(True)
+
+        # return the created action
+        return action
+
+    def _remove_action(self, action):
+        self._actions.remove(action)
+
+    def _add_container_actions(self, container):
+        # collect groups by titles
+        title_group_map = {}
+        for group in self._action_groups:
+            if group.title in title_group_map:
+                msg = _('cannot merge actions - two groups are named %r')
+                raise ValueError(msg % (group.title))
+            title_group_map[group.title] = group
+
+        # map each action to its group
+        group_map = {}
+        for group in container._action_groups:
+
+            # if a group with the title exists, use that, otherwise
+            # create a new group matching the container's group
+            if group.title not in title_group_map:
+                title_group_map[group.title] = self.add_argument_group(
+                    title=group.title,
+                    description=group.description,
+                    conflict_handler=group.conflict_handler)
+
+            # map the actions to their new group
+            for action in group._group_actions:
+                group_map[action] = title_group_map[group.title]
+
+        # add container's mutually exclusive groups
+        # NOTE: if add_mutually_exclusive_group ever gains title= and
+        # description= then this code will need to be expanded as above
+        for group in container._mutually_exclusive_groups:
+            mutex_group = self.add_mutually_exclusive_group(
+                required=group.required)
+
+            # map the actions to their new mutex group
+            for action in group._group_actions:
+                group_map[action] = mutex_group
+
+        # add all actions to this container or their group
+        for action in container._actions:
+            group_map.get(action, self)._add_action(action)
+
+    def _get_positional_kwargs(self, dest, **kwargs):
+        # make sure required is not specified
+        if 'required' in kwargs:
+            msg = _("'required' is an invalid argument for positionals")
+            raise TypeError(msg)
+
+        # mark positional arguments as required if at least one is
+        # always required
+        if kwargs.get('nargs') not in [OPTIONAL, ZERO_OR_MORE]:
+            kwargs['required'] = True
+        if kwargs.get('nargs') == ZERO_OR_MORE and 'default' not in kwargs:
+            kwargs['required'] = True
+
+        # return the keyword arguments with no option strings
+        return dict(kwargs, dest=dest, option_strings=[])
+
+    def _get_optional_kwargs(self, *args, **kwargs):
+        # determine short and long option strings
+        option_strings = []
+        long_option_strings = []
+        for option_string in args:
+            # error on strings that don't start with an appropriate prefix
+            if not option_string[0] in self.prefix_chars:
+                msg = _('invalid option string %r: '
+                        'must start with a character %r')
+                tup = option_string, self.prefix_chars
+                raise ValueError(msg % tup)
+
+            # strings starting with two prefix characters are long options
+            option_strings.append(option_string)
+            if option_string[0] in self.prefix_chars:
+                if len(option_string) > 1:
+                    if option_string[1] in self.prefix_chars:
+                        long_option_strings.append(option_string)
+
+        # infer destination, '--foo-bar' -> 'foo_bar' and '-x' -> 'x'
+        dest = kwargs.pop('dest', None)
+        if dest is None:
+            if long_option_strings:
+                dest_option_string = long_option_strings[0]
+            else:
+                dest_option_string = option_strings[0]
+            dest = dest_option_string.lstrip(self.prefix_chars)
+            if not dest:
+                msg = _('dest= is required for options like %r')
+                raise ValueError(msg % option_string)
+            dest = dest.replace('-', '_')
+
+        # return the updated keyword arguments
+        return dict(kwargs, dest=dest, option_strings=option_strings)
+
+    def _pop_action_class(self, kwargs, default=None):
+        action = kwargs.pop('action', default)
+        return self._registry_get('action', action, action)
+
+    def _get_handler(self):
+        # determine function from conflict handler string
+        handler_func_name = '_handle_conflict_%s' % self.conflict_handler
+        try:
+            return getattr(self, handler_func_name)
+        except AttributeError:
+            msg = _('invalid conflict_resolution value: %r')
+            raise ValueError(msg % self.conflict_handler)
+
+    def _check_conflict(self, action):
+
+        # find all options that conflict with this option
+        confl_optionals = []
+        for option_string in action.option_strings:
+            if option_string in self._option_string_actions:
+                confl_optional = self._option_string_actions[option_string]
+                confl_optionals.append((option_string, confl_optional))
+
+        # resolve any conflicts
+        if confl_optionals:
+            conflict_handler = self._get_handler()
+            conflict_handler(action, confl_optionals)
+
+    def _handle_conflict_error(self, action, conflicting_actions):
+        message = _('conflicting option string(s): %s')
+        conflict_string = ', '.join([option_string
+                                     for option_string, action
+                                     in conflicting_actions])
+        raise ArgumentError(action, message % conflict_string)
+
+    def _handle_conflict_resolve(self, action, conflicting_actions):
+
+        # remove all conflicting options
+        for option_string, action in conflicting_actions:
+
+            # remove the conflicting option
+            action.option_strings.remove(option_string)
+            self._option_string_actions.pop(option_string, None)
+
+            # if the option now has no option string, remove it from the
+            # container holding it
+            if not action.option_strings:
+                action.container._remove_action(action)
+
+
+class _ArgumentGroup(_ActionsContainer):
+
+    def __init__(self, container, title=None, description=None, **kwargs):
+        # add any missing keyword arguments by checking the container
+        update = kwargs.setdefault
+        update('conflict_handler', container.conflict_handler)
+        update('prefix_chars', container.prefix_chars)
+        update('argument_default', container.argument_default)
+        super_init = super(_ArgumentGroup, self).__init__
+        super_init(description=description, **kwargs)
+
+        # group attributes
+        self.title = title
+        self._group_actions = []
+
+        # share most attributes with the container
+        self._registries = container._registries
+        self._actions = container._actions
+        self._option_string_actions = container._option_string_actions
+        self._defaults = container._defaults
+        self._has_negative_number_optionals = \
+            container._has_negative_number_optionals
+
+    def _add_action(self, action):
+        action = super(_ArgumentGroup, self)._add_action(action)
+        self._group_actions.append(action)
+        return action
+
+    def _remove_action(self, action):
+        super(_ArgumentGroup, self)._remove_action(action)
+        self._group_actions.remove(action)
+
+
+class _MutuallyExclusiveGroup(_ArgumentGroup):
+
+    def __init__(self, container, required=False):
+        super(_MutuallyExclusiveGroup, self).__init__(container)
+        self.required = required
+        self._container = container
+
+    def _add_action(self, action):
+        if action.required:
+            msg = _('mutually exclusive arguments must be optional')
+            raise ValueError(msg)
+        action = self._container._add_action(action)
+        self._group_actions.append(action)
+        return action
+
+    def _remove_action(self, action):
+        self._container._remove_action(action)
+        self._group_actions.remove(action)
+
+
+class ArgumentParser(_AttributeHolder, _ActionsContainer):
+    """Object for parsing command line strings into Python objects.
+
+    Keyword Arguments:
+        - prog -- The name of the program (default: sys.argv[0])
+        - usage -- A usage message (default: auto-generated from arguments)
+        - description -- A description of what the program does
+        - epilog -- Text following the argument descriptions
+        - parents -- Parsers whose arguments should be copied into this one
+        - formatter_class -- HelpFormatter class for printing help messages
+        - prefix_chars -- Characters that prefix optional arguments
+        - fromfile_prefix_chars -- Characters that prefix files containing
+            additional arguments
+        - argument_default -- The default value for all arguments
+        - conflict_handler -- String indicating how to handle conflicts
+        - add_help -- Add a -h/-help option
+    """
+
+    def __init__(self,
+                 prog=None,
+                 usage=None,
+                 description=None,
+                 epilog=None,
+                 version=None,
+                 parents=[],
+                 formatter_class=HelpFormatter,
+                 prefix_chars='-',
+                 fromfile_prefix_chars=None,
+                 argument_default=None,
+                 conflict_handler='error',
+                 add_help=True):
+
+        if version is not None:
+            import warnings
+            warnings.warn(
+                """The "version" argument to ArgumentParser is deprecated. """
+                """Please use """
+                """"add_argument(..., action='version', version="N", ...)" """
+                """instead""", DeprecationWarning)
+
+        superinit = super(ArgumentParser, self).__init__
+        superinit(description=description,
+                  prefix_chars=prefix_chars,
+                  argument_default=argument_default,
+                  conflict_handler=conflict_handler)
+
+        # default setting for prog
+        if prog is None:
+            prog = _os.path.basename(_sys.argv[0])
+
+        self.prog = prog
+        self.usage = usage
+        self.epilog = epilog
+        self.version = version
+        self.formatter_class = formatter_class
+        self.fromfile_prefix_chars = fromfile_prefix_chars
+        self.add_help = add_help
+
+        add_group = self.add_argument_group
+        self._positionals = add_group(_('positional arguments'))
+        self._optionals = add_group(_('optional arguments'))
+        self._subparsers = None
+
+        # register types
+        def identity(string):
+            return string
+        self.register('type', None, identity)
+
+        # add help and version arguments if necessary
+        # (using explicit default to override global argument_default)
+        if self.add_help:
+            self.add_argument(
+                '-h', '--help', action='help', default=SUPPRESS,
+                help=_('show this help message and exit'))
+        if self.version:
+            self.add_argument(
+                '-v', '--version', action='version', default=SUPPRESS,
+                version=self.version,
+                help=_("show program's version number and exit"))
+
+        # add parent arguments and defaults
+        for parent in parents:
+            self._add_container_actions(parent)
+            try:
+                defaults = parent._defaults
+            except AttributeError:
+                pass
+            else:
+                self._defaults.update(defaults)
+
+    # =======================
+    # Pretty __repr__ methods
+    # =======================
+    def _get_kwargs(self):
+        names = [
+            'prog',
+            'usage',
+            'description',
+            'version',
+            'formatter_class',
+            'conflict_handler',
+            'add_help',
+        ]
+        return [(name, getattr(self, name)) for name in names]
+
+    # ==================================
+    # Optional/Positional adding methods
+    # ==================================
+    def add_subparsers(self, **kwargs):
+        if self._subparsers is not None:
+            self.error(_('cannot have multiple subparser arguments'))
+
+        # add the parser class to the arguments if it's not present
+        kwargs.setdefault('parser_class', type(self))
+
+        if 'title' in kwargs or 'description' in kwargs:
+            title = _(kwargs.pop('title', 'subcommands'))
+            description = _(kwargs.pop('description', None))
+            self._subparsers = self.add_argument_group(title, description)
+        else:
+            self._subparsers = self._positionals
+
+        # prog defaults to the usage message of this parser, skipping
+        # optional arguments and with no "usage:" prefix
+        if kwargs.get('prog') is None:
+            formatter = self._get_formatter()
+            positionals = self._get_positional_actions()
+            groups = self._mutually_exclusive_groups
+            formatter.add_usage(self.usage, positionals, groups, '')
+            kwargs['prog'] = formatter.format_help().strip()
+
+        # create the parsers action and add it to the positionals list
+        parsers_class = self._pop_action_class(kwargs, 'parsers')
+        action = parsers_class(option_strings=[], **kwargs)
+        self._subparsers._add_action(action)
+
+        # return the created parsers action
+        return action
+
+    def _add_action(self, action):
+        if action.option_strings:
+            self._optionals._add_action(action)
+        else:
+            self._positionals._add_action(action)
+        return action
+
+    def _get_optional_actions(self):
+        return [action
+                for action in self._actions
+                if action.option_strings]
+
+    def _get_positional_actions(self):
+        return [action
+                for action in self._actions
+                if not action.option_strings]
+
+    # =====================================
+    # Command line argument parsing methods
+    # =====================================
+    def parse_args(self, args=None, namespace=None):
+        args, argv = self.parse_known_args(args, namespace)
+        if argv:
+            msg = _('unrecognized arguments: %s')
+            self.error(msg % ' '.join(argv))
+        return args
+
+    def parse_known_args(self, args=None, namespace=None):
+        # args default to the system args
+        if args is None:
+            args = _sys.argv[1:]
+
+        # default Namespace built from parser defaults
+        if namespace is None:
+            namespace = Namespace()
+
+        # add any action defaults that aren't present
+        for action in self._actions:
+            if action.dest is not SUPPRESS:
+                if not hasattr(namespace, action.dest):
+                    if action.default is not SUPPRESS:
+                        default = action.default
+                        if isinstance(action.default, _basestring):
+                            default = self._get_value(action, default)
+                        setattr(namespace, action.dest, default)
+
+        # add any parser defaults that aren't present
+        for dest in self._defaults:
+            if not hasattr(namespace, dest):
+                setattr(namespace, dest, self._defaults[dest])
+
+        # parse the arguments and exit if there are any errors
+        try:
+            return self._parse_known_args(args, namespace)
+        except ArgumentError:
+            err = _sys.exc_info()[1]
+            self.error(str(err))
+
+    def _parse_known_args(self, arg_strings, namespace):
+        # replace arg strings that are file references
+        if self.fromfile_prefix_chars is not None:
+            arg_strings = self._read_args_from_files(arg_strings)
+
+        # map all mutually exclusive arguments to the other arguments
+        # they can't occur with
+        action_conflicts = {}
+        for mutex_group in self._mutually_exclusive_groups:
+            group_actions = mutex_group._group_actions
+            for i, mutex_action in enumerate(mutex_group._group_actions):
+                conflicts = action_conflicts.setdefault(mutex_action, [])
+                conflicts.extend(group_actions[:i])
+                conflicts.extend(group_actions[i + 1:])
+
+        # find all option indices, and determine the arg_string_pattern
+        # which has an 'O' if there is an option at an index,
+        # an 'A' if there is an argument, or a '-' if there is a '--'
+        option_string_indices = {}
+        arg_string_pattern_parts = []
+        arg_strings_iter = iter(arg_strings)
+        for i, arg_string in enumerate(arg_strings_iter):
+
+            # all args after -- are non-options
+            if arg_string == '--':
+                arg_string_pattern_parts.append('-')
+                for arg_string in arg_strings_iter:
+                    arg_string_pattern_parts.append('A')
+
+            # otherwise, add the arg to the arg strings
+            # and note the index if it was an option
+            else:
+                option_tuple = self._parse_optional(arg_string)
+                if option_tuple is None:
+                    pattern = 'A'
+                else:
+                    option_string_indices[i] = option_tuple
+                    pattern = 'O'
+                arg_string_pattern_parts.append(pattern)
+
+        # join the pieces together to form the pattern
+        arg_strings_pattern = ''.join(arg_string_pattern_parts)
+
+        # converts arg strings to the appropriate and then takes the action
+        seen_actions = _set()
+        seen_non_default_actions = _set()
+
+        def take_action(action, argument_strings, option_string=None):
+            seen_actions.add(action)
+            argument_values = self._get_values(action, argument_strings)
+
+            # error if this argument is not allowed with other previously
+            # seen arguments, assuming that actions that use the default
+            # value don't really count as "present"
+            if argument_values is not action.default:
+                seen_non_default_actions.add(action)
+                for conflict_action in action_conflicts.get(action, []):
+                    if conflict_action in seen_non_default_actions:
+                        msg = _('not allowed with argument %s')
+                        action_name = _get_action_name(conflict_action)
+                        raise ArgumentError(action, msg % action_name)
+
+            # take the action if we didn't receive a SUPPRESS value
+            # (e.g. from a default)
+            if argument_values is not SUPPRESS:
+                action(self, namespace, argument_values, option_string)
+
+        # function to convert arg_strings into an optional action
+        def consume_optional(start_index):
+
+            # get the optional identified at this index
+            option_tuple = option_string_indices[start_index]
+            action, option_string, explicit_arg = option_tuple
+
+            # identify additional optionals in the same arg string
+            # (e.g. -xyz is the same as -x -y -z if no args are required)
+            match_argument = self._match_argument
+            action_tuples = []
+            while True:
+
+                # if we found no optional action, skip it
+                if action is None:
+                    extras.append(arg_strings[start_index])
+                    return start_index + 1
+
+                # if there is an explicit argument, try to match the
+                # optional's string arguments to only this
+                if explicit_arg is not None:
+                    arg_count = match_argument(action, 'A')
+
+                    # if the action is a single-dash option and takes no
+                    # arguments, try to parse more single-dash options out
+                    # of the tail of the option string
+                    chars = self.prefix_chars
+                    if arg_count == 0 and option_string[1] not in chars:
+                        action_tuples.append((action, [], option_string))
+                        for char in self.prefix_chars:
+                            option_string = char + explicit_arg[0]
+                            explicit_arg = explicit_arg[1:] or None
+                            optionals_map = self._option_string_actions
+                            if option_string in optionals_map:
+                                action = optionals_map[option_string]
+                                break
+                        else:
+                            msg = _('ignored explicit argument %r')
+                            raise ArgumentError(action, msg % explicit_arg)
+
+                    # if the action expect exactly one argument, we've
+                    # successfully matched the option; exit the loop
+                    elif arg_count == 1:
+                        stop = start_index + 1
+                        args = [explicit_arg]
+                        action_tuples.append((action, args, option_string))
+                        break
+
+                    # error if a double-dash option did not use the
+                    # explicit argument
+                    else:
+                        msg = _('ignored explicit argument %r')
+                        raise ArgumentError(action, msg % explicit_arg)
+
+                # if there is no explicit argument, try to match the
+                # optional's string arguments with the following strings
+                # if successful, exit the loop
+                else:
+                    start = start_index + 1
+                    selected_patterns = arg_strings_pattern[start:]
+                    arg_count = match_argument(action, selected_patterns)
+                    stop = start + arg_count
+                    args = arg_strings[start:stop]
+                    action_tuples.append((action, args, option_string))
+                    break
+
+            # add the Optional to the list and return the index at which
+            # the Optional's string args stopped
+            assert action_tuples
+            for action, args, option_string in action_tuples:
+                take_action(action, args, option_string)
+            return stop
+
+        # the list of Positionals left to be parsed; this is modified
+        # by consume_positionals()
+        positionals = self._get_positional_actions()
+
+        # function to convert arg_strings into positional actions
+        def consume_positionals(start_index):
+            # match as many Positionals as possible
+            match_partial = self._match_arguments_partial
+            selected_pattern = arg_strings_pattern[start_index:]
+            arg_counts = match_partial(positionals, selected_pattern)
+
+            # slice off the appropriate arg strings for each Positional
+            # and add the Positional and its args to the list
+            for action, arg_count in zip(positionals, arg_counts):
+                args = arg_strings[start_index: start_index + arg_count]
+                start_index += arg_count
+                take_action(action, args)
+
+            # slice off the Positionals that we just parsed and return the
+            # index at which the Positionals' string args stopped
+            positionals[:] = positionals[len(arg_counts):]
+            return start_index
+
+        # consume Positionals and Optionals alternately, until we have
+        # passed the last option string
+        extras = []
+        start_index = 0
+        if option_string_indices:
+            max_option_string_index = max(option_string_indices)
+        else:
+            max_option_string_index = -1
+        while start_index <= max_option_string_index:
+
+            # consume any Positionals preceding the next option
+            next_option_string_index = min([
+                index
+                for index in option_string_indices
+                if index >= start_index])
+            if start_index != next_option_string_index:
+                positionals_end_index = consume_positionals(start_index)
+
+                # only try to parse the next optional if we didn't consume
+                # the option string during the positionals parsing
+                if positionals_end_index > start_index:
+                    start_index = positionals_end_index
+                    continue
+                else:
+                    start_index = positionals_end_index
+
+            # if we consumed all the positionals we could and we're not
+            # at the index of an option string, there were extra arguments
+            if start_index not in option_string_indices:
+                strings = arg_strings[start_index:next_option_string_index]
+                extras.extend(strings)
+                start_index = next_option_string_index
+
+            # consume the next optional and any arguments for it
+            start_index = consume_optional(start_index)
+
+        # consume any positionals following the last Optional
+        stop_index = consume_positionals(start_index)
+
+        # if we didn't consume all the argument strings, there were extras
+        extras.extend(arg_strings[stop_index:])
+
+        # if we didn't use all the Positional objects, there were too few
+        # arg strings supplied.
+        if positionals:
+            self.error(_('too few arguments'))
+
+        # make sure all required actions were present
+        for action in self._actions:
+            if action.required:
+                if action not in seen_actions:
+                    name = _get_action_name(action)
+                    self.error(_('argument %s is required') % name)
+
+        # make sure all required groups had one option present
+        for group in self._mutually_exclusive_groups:
+            if group.required:
+                for action in group._group_actions:
+                    if action in seen_non_default_actions:
+                        break
+
+                # if no actions were used, report the error
+                else:
+                    names = [_get_action_name(action)
+                             for action in group._group_actions
+                             if action.help is not SUPPRESS]
+                    msg = _('one of the arguments %s is required')
+                    self.error(msg % ' '.join(names))
+
+        # return the updated namespace and the extra arguments
+        return namespace, extras
+
+    def _read_args_from_files(self, arg_strings):
+        # expand arguments referencing files
+        new_arg_strings = []
+        for arg_string in arg_strings:
+
+            # for regular arguments, just add them back into the list
+            if arg_string[0] not in self.fromfile_prefix_chars:
+                new_arg_strings.append(arg_string)
+
+            # replace arguments referencing files with the file content
+            else:
+                try:
+                    args_file = open(arg_string[1:])
+                    try:
+                        arg_strings = []
+                        for arg_line in args_file.read().splitlines():
+                            for arg in self.convert_arg_line_to_args(arg_line):
+                                arg_strings.append(arg)
+                        arg_strings = self._read_args_from_files(arg_strings)
+                        new_arg_strings.extend(arg_strings)
+                    finally:
+                        args_file.close()
+                except IOError:
+                    err = _sys.exc_info()[1]
+                    self.error(str(err))
+
+        # return the modified argument list
+        return new_arg_strings
+
+    def convert_arg_line_to_args(self, arg_line):
+        return [arg_line]
+
+    def _match_argument(self, action, arg_strings_pattern):
+        # match the pattern for this action to the arg strings
+        nargs_pattern = self._get_nargs_pattern(action)
+        match = _re.match(nargs_pattern, arg_strings_pattern)
+
+        # raise an exception if we weren't able to find a match
+        if match is None:
+            nargs_errors = {
+                None: _('expected one argument'),
+                OPTIONAL: _('expected at most one argument'),
+                ONE_OR_MORE: _('expected at least one argument'),
+            }
+            default = _('expected %s argument(s)') % action.nargs
+            msg = nargs_errors.get(action.nargs, default)
+            raise ArgumentError(action, msg)
+
+        # return the number of arguments matched
+        return len(match.group(1))
+
+    def _match_arguments_partial(self, actions, arg_strings_pattern):
+        # progressively shorten the actions list by slicing off the
+        # final actions until we find a match
+        result = []
+        for i in range(len(actions), 0, -1):
+            actions_slice = actions[:i]
+            pattern = ''.join([self._get_nargs_pattern(action)
+                               for action in actions_slice])
+            match = _re.match(pattern, arg_strings_pattern)
+            if match is not None:
+                result.extend([len(string) for string in match.groups()])
+                break
+
+        # return the list of arg string counts
+        return result
+
+    def _parse_optional(self, arg_string):
+        # if it's an empty string, it was meant to be a positional
+        if not arg_string:
+            return None
+
+        # if it doesn't start with a prefix, it was meant to be positional
+        if not arg_string[0] in self.prefix_chars:
+            return None
+
+        # if the option string is present in the parser, return the action
+        if arg_string in self._option_string_actions:
+            action = self._option_string_actions[arg_string]
+            return action, arg_string, None
+
+        # if it's just a single character, it was meant to be positional
+        if len(arg_string) == 1:
+            return None
+
+        # if the option string before the "=" is present, return the action
+        if '=' in arg_string:
+            option_string, explicit_arg = arg_string.split('=', 1)
+            if option_string in self._option_string_actions:
+                action = self._option_string_actions[option_string]
+                return action, option_string, explicit_arg
+
+        # search through all possible prefixes of the option string
+        # and all actions in the parser for possible interpretations
+        option_tuples = self._get_option_tuples(arg_string)
+
+        # if multiple actions match, the option string was ambiguous
+        if len(option_tuples) > 1:
+            options = ', '.join([option_string
+                for action, option_string, explicit_arg in option_tuples])
+            tup = arg_string, options
+            self.error(_('ambiguous option: %s could match %s') % tup)
+
+        # if exactly one action matched, this segmentation is good,
+        # so return the parsed action
+        elif len(option_tuples) == 1:
+            option_tuple, = option_tuples
+            return option_tuple
+
+        # if it was not found as an option, but it looks like a negative
+        # number, it was meant to be positional
+        # unless there are negative-number-like options
+        if self._negative_number_matcher.match(arg_string):
+            if not self._has_negative_number_optionals:
+                return None
+
+        # if it contains a space, it was meant to be a positional
+        if ' ' in arg_string:
+            return None
+
+        # it was meant to be an optional but there is no such option
+        # in this parser (though it might be a valid option in a subparser)
+        return None, arg_string, None
+
+    def _get_option_tuples(self, option_string):
+        result = []
+
+        # option strings starting with two prefix characters are only
+        # split at the '='
+        chars = self.prefix_chars
+        if option_string[0] in chars and option_string[1] in chars:
+            if '=' in option_string:
+                option_prefix, explicit_arg = option_string.split('=', 1)
+            else:
+                option_prefix = option_string
+                explicit_arg = None
+            for option_string in self._option_string_actions:
+                if option_string.startswith(option_prefix):
+                    action = self._option_string_actions[option_string]
+                    tup = action, option_string, explicit_arg
+                    result.append(tup)
+
+        # single character options can be concatenated with their arguments
+        # but multiple character options always have to have their argument
+        # separate
+        elif option_string[0] in chars and option_string[1] not in chars:
+            option_prefix = option_string
+            explicit_arg = None
+            short_option_prefix = option_string[:2]
+            short_explicit_arg = option_string[2:]
+
+            for option_string in self._option_string_actions:
+                if option_string == short_option_prefix:
+                    action = self._option_string_actions[option_string]
+                    tup = action, option_string, short_explicit_arg
+                    result.append(tup)
+                elif option_string.startswith(option_prefix):
+                    action = self._option_string_actions[option_string]
+                    tup = action, option_string, explicit_arg
+                    result.append(tup)
+
+        # shouldn't ever get here
+        else:
+            self.error(_('unexpected option string: %s') % option_string)
+
+        # return the collected option tuples
+        return result
+
+    def _get_nargs_pattern(self, action):
+        # in all examples below, we have to allow for '--' args
+        # which are represented as '-' in the pattern
+        nargs = action.nargs
+
+        # the default (None) is assumed to be a single argument
+        if nargs is None:
+            nargs_pattern = '(-*A-*)'
+
+        # allow zero or one arguments
+        elif nargs == OPTIONAL:
+            nargs_pattern = '(-*A?-*)'
+
+        # allow zero or more arguments
+        elif nargs == ZERO_OR_MORE:
+            nargs_pattern = '(-*[A-]*)'
+
+        # allow one or more arguments
+        elif nargs == ONE_OR_MORE:
+            nargs_pattern = '(-*A[A-]*)'
+
+        # allow any number of options or arguments
+        elif nargs == REMAINDER:
+            nargs_pattern = '([-AO]*)'
+
+        # allow one argument followed by any number of options or arguments
+        elif nargs == PARSER:
+            nargs_pattern = '(-*A[-AO]*)'
+
+        # all others should be integers
+        else:
+            nargs_pattern = '(-*%s-*)' % '-*'.join('A' * nargs)
+
+        # if this is an optional action, -- is not allowed
+        if action.option_strings:
+            nargs_pattern = nargs_pattern.replace('-*', '')
+            nargs_pattern = nargs_pattern.replace('-', '')
+
+        # return the pattern
+        return nargs_pattern
+
+    # ========================
+    # Value conversion methods
+    # ========================
+    def _get_values(self, action, arg_strings):
+        # for everything but PARSER args, strip out '--'
+        if action.nargs not in [PARSER, REMAINDER]:
+            arg_strings = [s for s in arg_strings if s != '--']
+
+        # optional argument produces a default when not present
+        if not arg_strings and action.nargs == OPTIONAL:
+            if action.option_strings:
+                value = action.const
+            else:
+                value = action.default
+            if isinstance(value, _basestring):
+                value = self._get_value(action, value)
+                self._check_value(action, value)
+
+        # when nargs='*' on a positional, if there were no command-line
+        # args, use the default if it is anything other than None
+        elif (not arg_strings and action.nargs == ZERO_OR_MORE and
+              not action.option_strings):
+            if action.default is not None:
+                value = action.default
+            else:
+                value = arg_strings
+            self._check_value(action, value)
+
+        # single argument or optional argument produces a single value
+        elif len(arg_strings) == 1 and action.nargs in [None, OPTIONAL]:
+            arg_string, = arg_strings
+            value = self._get_value(action, arg_string)
+            self._check_value(action, value)
+
+        # REMAINDER arguments convert all values, checking none
+        elif action.nargs == REMAINDER:
+            value = [self._get_value(action, v) for v in arg_strings]
+
+        # PARSER arguments convert all values, but check only the first
+        elif action.nargs == PARSER:
+            value = [self._get_value(action, v) for v in arg_strings]
+            self._check_value(action, value[0])
+
+        # all other types of nargs produce a list
+        else:
+            value = [self._get_value(action, v) for v in arg_strings]
+            for v in value:
+                self._check_value(action, v)
+
+        # return the converted value
+        return value
+
+    def _get_value(self, action, arg_string):
+        type_func = self._registry_get('type', action.type, action.type)
+        if not _callable(type_func):
+            msg = _('%r is not callable')
+            raise ArgumentError(action, msg % type_func)
+
+        # convert the value to the appropriate type
+        try:
+            result = type_func(arg_string)
+
+        # ArgumentTypeErrors indicate errors
+        except ArgumentTypeError:
+            name = getattr(action.type, '__name__', repr(action.type))
+            msg = str(_sys.exc_info()[1])
+            raise ArgumentError(action, msg)
+
+        # TypeErrors or ValueErrors also indicate errors
+        except (TypeError, ValueError):
+            name = getattr(action.type, '__name__', repr(action.type))
+            msg = _('invalid %s value: %r')
+            raise ArgumentError(action, msg % (name, arg_string))
+
+        # return the converted value
+        return result
+
+    def _check_value(self, action, value):
+        # converted value must be one of the choices (if specified)
+        if action.choices is not None and value not in action.choices:
+            tup = value, ', '.join(map(repr, action.choices))
+            msg = _('invalid choice: %r (choose from %s)') % tup
+            raise ArgumentError(action, msg)
+
+    # =======================
+    # Help-formatting methods
+    # =======================
+    def format_usage(self):
+        formatter = self._get_formatter()
+        formatter.add_usage(self.usage, self._actions,
+                            self._mutually_exclusive_groups)
+        return formatter.format_help()
+
+    def format_help(self):
+        formatter = self._get_formatter()
+
+        # usage
+        formatter.add_usage(self.usage, self._actions,
+                            self._mutually_exclusive_groups)
+
+        # description
+        formatter.add_text(self.description)
+
+        # positionals, optionals and user-defined groups
+        for action_group in self._action_groups:
+            formatter.start_section(action_group.title)
+            formatter.add_text(action_group.description)
+            formatter.add_arguments(action_group._group_actions)
+            formatter.end_section()
+
+        # epilog
+        formatter.add_text(self.epilog)
+
+        # determine help from format above
+        return formatter.format_help()
+
+    def format_version(self):
+        import warnings
+        warnings.warn(
+            'The format_version method is deprecated -- the "version" '
+            'argument to ArgumentParser is no longer supported.',
+            DeprecationWarning)
+        formatter = self._get_formatter()
+        formatter.add_text(self.version)
+        return formatter.format_help()
+
+    def _get_formatter(self):
+        return self.formatter_class(prog=self.prog)
+
+    # =====================
+    # Help-printing methods
+    # =====================
+    def print_usage(self, file=None):
+        if file is None:
+            file = _sys.stdout
+        self._print_message(self.format_usage(), file)
+
+    def print_help(self, file=None):
+        if file is None:
+            file = _sys.stdout
+        self._print_message(self.format_help(), file)
+
+    def print_version(self, file=None):
+        import warnings
+        warnings.warn(
+            'The print_version method is deprecated -- the "version" '
+            'argument to ArgumentParser is no longer supported.',
+            DeprecationWarning)
+        self._print_message(self.format_version(), file)
+
+    def _print_message(self, message, file=None):
+        if message:
+            if file is None:
+                file = _sys.stderr
+            file.write(message)
+
+    # ===============
+    # Exiting methods
+    # ===============
+    def exit(self, status=0, message=None):
+        if message:
+            self._print_message(message, _sys.stderr)
+        _sys.exit(status)
+
+    def error(self, message):
+        """error(message: string)
+
+        Prints a usage message incorporating the message to stderr and
+        exits.
+
+        If you override this in a subclass, it should not return -- it
+        should either exit or raise an exception.
+        """
+        self.print_usage(_sys.stderr)
+        self.exit(2, _('%s: error: %s\n') % (self.prog, message))