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+
+:mod:`difflib` --- Helpers for computing deltas
+===============================================
+
+.. module:: difflib
+   :synopsis: Helpers for computing differences between objects.
+.. moduleauthor:: Tim Peters <tim_one@users.sourceforge.net>
+.. sectionauthor:: Tim Peters <tim_one@users.sourceforge.net>
+
+
+.. % LaTeXification by Fred L. Drake, Jr. <fdrake@acm.org>.
+
+.. versionadded:: 2.1
+
+
+.. class:: SequenceMatcher
+
+   This is a flexible class for comparing pairs of sequences of any type, so long
+   as the sequence elements are hashable.  The basic algorithm predates, and is a
+   little fancier than, an algorithm published in the late 1980's by Ratcliff and
+   Obershelp under the hyperbolic name "gestalt pattern matching."  The idea is to
+   find the longest contiguous matching subsequence that contains no "junk"
+   elements (the Ratcliff and Obershelp algorithm doesn't address junk).  The same
+   idea is then applied recursively to the pieces of the sequences to the left and
+   to the right of the matching subsequence.  This does not yield minimal edit
+   sequences, but does tend to yield matches that "look right" to people.
+
+   **Timing:** The basic Ratcliff-Obershelp algorithm is cubic time in the worst
+   case and quadratic time in the expected case. :class:`SequenceMatcher` is
+   quadratic time for the worst case and has expected-case behavior dependent in a
+   complicated way on how many elements the sequences have in common; best case
+   time is linear.
+
+
+.. class:: Differ
+
+   This is a class for comparing sequences of lines of text, and producing
+   human-readable differences or deltas.  Differ uses :class:`SequenceMatcher`
+   both to compare sequences of lines, and to compare sequences of characters
+   within similar (near-matching) lines.
+
+   Each line of a :class:`Differ` delta begins with a two-letter code:
+
+   +----------+-------------------------------------------+
+   | Code     | Meaning                                   |
+   +==========+===========================================+
+   | ``'- '`` | line unique to sequence 1                 |
+   +----------+-------------------------------------------+
+   | ``'+ '`` | line unique to sequence 2                 |
+   +----------+-------------------------------------------+
+   | ``'  '`` | line common to both sequences             |
+   +----------+-------------------------------------------+
+   | ``'? '`` | line not present in either input sequence |
+   +----------+-------------------------------------------+
+
+   Lines beginning with '``?``' attempt to guide the eye to intraline differences,
+   and were not present in either input sequence. These lines can be confusing if
+   the sequences contain tab characters.
+
+
+.. class:: HtmlDiff
+
+   This class can be used to create an HTML table (or a complete HTML file
+   containing the table) showing a side by side, line by line comparison of text
+   with inter-line and intra-line change highlights.  The table can be generated in
+   either full or contextual difference mode.
+
+   The constructor for this class is:
+
+
+   .. function:: __init__([tabsize][, wrapcolumn][, linejunk][, charjunk])
+
+      Initializes instance of :class:`HtmlDiff`.
+
+      *tabsize* is an optional keyword argument to specify tab stop spacing and
+      defaults to ``8``.
+
+      *wrapcolumn* is an optional keyword to specify column number where lines are
+      broken and wrapped, defaults to ``None`` where lines are not wrapped.
+
+      *linejunk* and *charjunk* are optional keyword arguments passed into ``ndiff()``
+      (used by :class:`HtmlDiff` to generate the side by side HTML differences).  See
+      ``ndiff()`` documentation for argument default values and descriptions.
+
+   The following methods are public:
+
+
+   .. function:: make_file(fromlines, tolines [, fromdesc][, todesc][, context][, numlines])
+
+      Compares *fromlines* and *tolines* (lists of strings) and returns a string which
+      is a complete HTML file containing a table showing line by line differences with
+      inter-line and intra-line changes highlighted.
+
+      *fromdesc* and *todesc* are optional keyword arguments to specify from/to file
+      column header strings (both default to an empty string).
+
+      *context* and *numlines* are both optional keyword arguments. Set *context* to
+      ``True`` when contextual differences are to be shown, else the default is
+      ``False`` to show the full files. *numlines* defaults to ``5``.  When *context*
+      is ``True`` *numlines* controls the number of context lines which surround the
+      difference highlights.  When *context* is ``False`` *numlines* controls the
+      number of lines which are shown before a difference highlight when using the
+      "next" hyperlinks (setting to zero would cause the "next" hyperlinks to place
+      the next difference highlight at the top of the browser without any leading
+      context).
+
+
+   .. function:: make_table(fromlines, tolines [, fromdesc][, todesc][, context][, numlines])
+
+      Compares *fromlines* and *tolines* (lists of strings) and returns a string which
+      is a complete HTML table showing line by line differences with inter-line and
+      intra-line changes highlighted.
+
+      The arguments for this method are the same as those for the :meth:`make_file`
+      method.
+
+   :file:`Tools/scripts/diff.py` is a command-line front-end to this class and
+   contains a good example of its use.
+
+   .. versionadded:: 2.4
+
+
+.. function:: context_diff(a, b[, fromfile][, tofile][, fromfiledate][, tofiledate][, n][, lineterm])
+
+   Compare *a* and *b* (lists of strings); return a delta (a generator generating
+   the delta lines) in context diff format.
+
+   Context diffs are a compact way of showing just the lines that have changed plus
+   a few lines of context.  The changes are shown in a before/after style.  The
+   number of context lines is set by *n* which defaults to three.
+
+   By default, the diff control lines (those with ``***`` or ``---``) are created
+   with a trailing newline.  This is helpful so that inputs created from
+   :func:`file.readlines` result in diffs that are suitable for use with
+   :func:`file.writelines` since both the inputs and outputs have trailing
+   newlines.
+
+   For inputs that do not have trailing newlines, set the *lineterm* argument to
+   ``""`` so that the output will be uniformly newline free.
+
+   The context diff format normally has a header for filenames and modification
+   times.  Any or all of these may be specified using strings for *fromfile*,
+   *tofile*, *fromfiledate*, and *tofiledate*. The modification times are normally
+   expressed in the format returned by :func:`time.ctime`.  If not specified, the
+   strings default to blanks.
+
+   :file:`Tools/scripts/diff.py` is a command-line front-end for this function.
+
+   .. versionadded:: 2.3
+
+
+.. function:: get_close_matches(word, possibilities[, n][, cutoff])
+
+   Return a list of the best "good enough" matches.  *word* is a sequence for which
+   close matches are desired (typically a string), and *possibilities* is a list of
+   sequences against which to match *word* (typically a list of strings).
+
+   Optional argument *n* (default ``3``) is the maximum number of close matches to
+   return; *n* must be greater than ``0``.
+
+   Optional argument *cutoff* (default ``0.6``) is a float in the range [0, 1].
+   Possibilities that don't score at least that similar to *word* are ignored.
+
+   The best (no more than *n*) matches among the possibilities are returned in a
+   list, sorted by similarity score, most similar first. ::
+
+      >>> get_close_matches('appel', ['ape', 'apple', 'peach', 'puppy'])
+      ['apple', 'ape']
+      >>> import keyword
+      >>> get_close_matches('wheel', keyword.kwlist)
+      ['while']
+      >>> get_close_matches('apple', keyword.kwlist)
+      []
+      >>> get_close_matches('accept', keyword.kwlist)
+      ['except']
+
+
+.. function:: ndiff(a, b[, linejunk][, charjunk])
+
+   Compare *a* and *b* (lists of strings); return a :class:`Differ`\ -style delta
+   (a generator generating the delta lines).
+
+   Optional keyword parameters *linejunk* and *charjunk* are for filter functions
+   (or ``None``):
+
+   *linejunk*: A function that accepts a single string argument, and returns true
+   if the string is junk, or false if not. The default is (``None``), starting with
+   Python 2.3.  Before then, the default was the module-level function
+   :func:`IS_LINE_JUNK`, which filters out lines without visible characters, except
+   for at most one pound character (``'#'``). As of Python 2.3, the underlying
+   :class:`SequenceMatcher` class does a dynamic analysis of which lines are so
+   frequent as to constitute noise, and this usually works better than the pre-2.3
+   default.
+
+   *charjunk*: A function that accepts a character (a string of length 1), and
+   returns if the character is junk, or false if not. The default is module-level
+   function :func:`IS_CHARACTER_JUNK`, which filters out whitespace characters (a
+   blank or tab; note: bad idea to include newline in this!).
+
+   :file:`Tools/scripts/ndiff.py` is a command-line front-end to this function. ::
+
+      >>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1),
+      ...              'ore\ntree\nemu\n'.splitlines(1))
+      >>> print ''.join(diff),
+      - one
+      ?  ^
+      + ore
+      ?  ^
+      - two
+      - three
+      ?  -
+      + tree
+      + emu
+
+
+.. function:: restore(sequence, which)
+
+   Return one of the two sequences that generated a delta.
+
+   Given a *sequence* produced by :meth:`Differ.compare` or :func:`ndiff`, extract
+   lines originating from file 1 or 2 (parameter *which*), stripping off line
+   prefixes.
+
+   Example::
+
+      >>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1),
+      ...              'ore\ntree\nemu\n'.splitlines(1))
+      >>> diff = list(diff) # materialize the generated delta into a list
+      >>> print ''.join(restore(diff, 1)),
+      one
+      two
+      three
+      >>> print ''.join(restore(diff, 2)),
+      ore
+      tree
+      emu
+
+
+.. function:: unified_diff(a, b[, fromfile][, tofile][, fromfiledate][, tofiledate][, n][, lineterm])
+
+   Compare *a* and *b* (lists of strings); return a delta (a generator generating
+   the delta lines) in unified diff format.
+
+   Unified diffs are a compact way of showing just the lines that have changed plus
+   a few lines of context.  The changes are shown in a inline style (instead of
+   separate before/after blocks).  The number of context lines is set by *n* which
+   defaults to three.
+
+   By default, the diff control lines (those with ``---``, ``+++``, or ``@@``) are
+   created with a trailing newline.  This is helpful so that inputs created from
+   :func:`file.readlines` result in diffs that are suitable for use with
+   :func:`file.writelines` since both the inputs and outputs have trailing
+   newlines.
+
+   For inputs that do not have trailing newlines, set the *lineterm* argument to
+   ``""`` so that the output will be uniformly newline free.
+
+   The context diff format normally has a header for filenames and modification
+   times.  Any or all of these may be specified using strings for *fromfile*,
+   *tofile*, *fromfiledate*, and *tofiledate*. The modification times are normally
+   expressed in the format returned by :func:`time.ctime`.  If not specified, the
+   strings default to blanks.
+
+   :file:`Tools/scripts/diff.py` is a command-line front-end for this function.
+
+   .. versionadded:: 2.3
+
+
+.. function:: IS_LINE_JUNK(line)
+
+   Return true for ignorable lines.  The line *line* is ignorable if *line* is
+   blank or contains a single ``'#'``, otherwise it is not ignorable.  Used as a
+   default for parameter *linejunk* in :func:`ndiff` before Python 2.3.
+
+
+.. function:: IS_CHARACTER_JUNK(ch)
+
+   Return true for ignorable characters.  The character *ch* is ignorable if *ch*
+   is a space or tab, otherwise it is not ignorable.  Used as a default for
+   parameter *charjunk* in :func:`ndiff`.
+
+
+.. seealso::
+
+   `Pattern Matching: The Gestalt Approach <http://www.ddj.com/184407970?pgno=5>`_
+      Discussion of a similar algorithm by John W. Ratcliff and D. E. Metzener. This
+      was published in `Dr. Dobb's Journal <http://www.ddj.com/>`_ in July, 1988.
+
+
+.. _sequence-matcher:
+
+SequenceMatcher Objects
+-----------------------
+
+The :class:`SequenceMatcher` class has this constructor:
+
+
+.. class:: SequenceMatcher([isjunk[, a[, b]]])
+
+   Optional argument *isjunk* must be ``None`` (the default) or a one-argument
+   function that takes a sequence element and returns true if and only if the
+   element is "junk" and should be ignored. Passing ``None`` for *isjunk* is
+   equivalent to passing ``lambda x: 0``; in other words, no elements are ignored.
+   For example, pass::
+
+      lambda x: x in " \t"
+
+   if you're comparing lines as sequences of characters, and don't want to synch up
+   on blanks or hard tabs.
+
+   The optional arguments *a* and *b* are sequences to be compared; both default to
+   empty strings.  The elements of both sequences must be hashable.
+
+:class:`SequenceMatcher` objects have the following methods:
+
+
+.. method:: SequenceMatcher.set_seqs(a, b)
+
+   Set the two sequences to be compared.
+
+:class:`SequenceMatcher` computes and caches detailed information about the
+second sequence, so if you want to compare one sequence against many sequences,
+use :meth:`set_seq2` to set the commonly used sequence once and call
+:meth:`set_seq1` repeatedly, once for each of the other sequences.
+
+
+.. method:: SequenceMatcher.set_seq1(a)
+
+   Set the first sequence to be compared.  The second sequence to be compared is
+   not changed.
+
+
+.. method:: SequenceMatcher.set_seq2(b)
+
+   Set the second sequence to be compared.  The first sequence to be compared is
+   not changed.
+
+
+.. method:: SequenceMatcher.find_longest_match(alo, ahi, blo, bhi)
+
+   Find longest matching block in ``a[alo:ahi]`` and ``b[blo:bhi]``.
+
+   If *isjunk* was omitted or ``None``, :meth:`get_longest_match` returns ``(i, j,
+   k)`` such that ``a[i:i+k]`` is equal to ``b[j:j+k]``, where ``alo <= i <= i+k <=
+   ahi`` and ``blo <= j <= j+k <= bhi``. For all ``(i', j', k')`` meeting those
+   conditions, the additional conditions ``k >= k'``, ``i <= i'``, and if ``i ==
+   i'``, ``j <= j'`` are also met. In other words, of all maximal matching blocks,
+   return one that starts earliest in *a*, and of all those maximal matching blocks
+   that start earliest in *a*, return the one that starts earliest in *b*. ::
+
+      >>> s = SequenceMatcher(None, " abcd", "abcd abcd")
+      >>> s.find_longest_match(0, 5, 0, 9)
+      (0, 4, 5)
+
+   If *isjunk* was provided, first the longest matching block is determined as
+   above, but with the additional restriction that no junk element appears in the
+   block.  Then that block is extended as far as possible by matching (only) junk
+   elements on both sides. So the resulting block never matches on junk except as
+   identical junk happens to be adjacent to an interesting match.
+
+   Here's the same example as before, but considering blanks to be junk. That
+   prevents ``' abcd'`` from matching the ``' abcd'`` at the tail end of the second
+   sequence directly.  Instead only the ``'abcd'`` can match, and matches the
+   leftmost ``'abcd'`` in the second sequence::
+
+      >>> s = SequenceMatcher(lambda x: x==" ", " abcd", "abcd abcd")
+      >>> s.find_longest_match(0, 5, 0, 9)
+      (1, 0, 4)
+
+   If no blocks match, this returns ``(alo, blo, 0)``.
+
+
+.. method:: SequenceMatcher.get_matching_blocks()
+
+   Return list of triples describing matching subsequences. Each triple is of the
+   form ``(i, j, n)``, and means that ``a[i:i+n] == b[j:j+n]``.  The triples are
+   monotonically increasing in *i* and *j*.
+
+   The last triple is a dummy, and has the value ``(len(a), len(b), 0)``.  It is
+   the only triple with ``n == 0``.  If ``(i, j, n)`` and ``(i', j', n')`` are
+   adjacent triples in the list, and the second is not the last triple in the list,
+   then ``i+n != i'`` or ``j+n != j'``; in other words, adjacent triples always
+   describe non-adjacent equal blocks.
+
+   .. % Explain why a dummy is used!
+
+   .. versionchanged:: 2.5
+      The guarantee that adjacent triples always describe non-adjacent blocks was
+      implemented.
+
+   ::
+
+      >>> s = SequenceMatcher(None, "abxcd", "abcd")
+      >>> s.get_matching_blocks()
+      [(0, 0, 2), (3, 2, 2), (5, 4, 0)]
+
+
+.. method:: SequenceMatcher.get_opcodes()
+
+   Return list of 5-tuples describing how to turn *a* into *b*. Each tuple is of
+   the form ``(tag, i1, i2, j1, j2)``.  The first tuple has ``i1 == j1 == 0``, and
+   remaining tuples have *i1* equal to the *i2* from the preceding tuple, and,
+   likewise, *j1* equal to the previous *j2*.
+
+   The *tag* values are strings, with these meanings:
+
+   +---------------+---------------------------------------------+
+   | Value         | Meaning                                     |
+   +===============+=============================================+
+   | ``'replace'`` | ``a[i1:i2]`` should be replaced by          |
+   |               | ``b[j1:j2]``.                               |
+   +---------------+---------------------------------------------+
+   | ``'delete'``  | ``a[i1:i2]`` should be deleted.  Note that  |
+   |               | ``j1 == j2`` in this case.                  |
+   +---------------+---------------------------------------------+
+   | ``'insert'``  | ``b[j1:j2]`` should be inserted at          |
+   |               | ``a[i1:i1]``. Note that ``i1 == i2`` in     |
+   |               | this case.                                  |
+   +---------------+---------------------------------------------+
+   | ``'equal'``   | ``a[i1:i2] == b[j1:j2]`` (the sub-sequences |
+   |               | are equal).                                 |
+   +---------------+---------------------------------------------+
+
+   For example::
+
+      >>> a = "qabxcd"
+      >>> b = "abycdf"
+      >>> s = SequenceMatcher(None, a, b)
+      >>> for tag, i1, i2, j1, j2 in s.get_opcodes():
+      ...    print ("%7s a[%d:%d] (%s) b[%d:%d] (%s)" %
+      ...           (tag, i1, i2, a[i1:i2], j1, j2, b[j1:j2]))
+       delete a[0:1] (q) b[0:0] ()
+        equal a[1:3] (ab) b[0:2] (ab)
+      replace a[3:4] (x) b[2:3] (y)
+        equal a[4:6] (cd) b[3:5] (cd)
+       insert a[6:6] () b[5:6] (f)
+
+
+.. method:: SequenceMatcher.get_grouped_opcodes([n])
+
+   Return a generator of groups with up to *n* lines of context.
+
+   Starting with the groups returned by :meth:`get_opcodes`, this method splits out
+   smaller change clusters and eliminates intervening ranges which have no changes.
+
+   The groups are returned in the same format as :meth:`get_opcodes`.
+
+   .. versionadded:: 2.3
+
+
+.. method:: SequenceMatcher.ratio()
+
+   Return a measure of the sequences' similarity as a float in the range [0, 1].
+
+   Where T is the total number of elements in both sequences, and M is the number
+   of matches, this is 2.0\*M / T. Note that this is ``1.0`` if the sequences are
+   identical, and ``0.0`` if they have nothing in common.
+
+   This is expensive to compute if :meth:`get_matching_blocks` or
+   :meth:`get_opcodes` hasn't already been called, in which case you may want to
+   try :meth:`quick_ratio` or :meth:`real_quick_ratio` first to get an upper bound.
+
+
+.. method:: SequenceMatcher.quick_ratio()
+
+   Return an upper bound on :meth:`ratio` relatively quickly.
+
+   This isn't defined beyond that it is an upper bound on :meth:`ratio`, and is
+   faster to compute.
+
+
+.. method:: SequenceMatcher.real_quick_ratio()
+
+   Return an upper bound on :meth:`ratio` very quickly.
+
+   This isn't defined beyond that it is an upper bound on :meth:`ratio`, and is
+   faster to compute than either :meth:`ratio` or :meth:`quick_ratio`.
+
+The three methods that return the ratio of matching to total characters can give
+different results due to differing levels of approximation, although
+:meth:`quick_ratio` and :meth:`real_quick_ratio` are always at least as large as
+:meth:`ratio`::
+
+   >>> s = SequenceMatcher(None, "abcd", "bcde")
+   >>> s.ratio()
+   0.75
+   >>> s.quick_ratio()
+   0.75
+   >>> s.real_quick_ratio()
+   1.0
+
+
+.. _sequencematcher-examples:
+
+SequenceMatcher Examples
+------------------------
+
+This example compares two strings, considering blanks to be "junk:" ::
+
+   >>> s = SequenceMatcher(lambda x: x == " ",
+   ...                     "private Thread currentThread;",
+   ...                     "private volatile Thread currentThread;")
+
+:meth:`ratio` returns a float in [0, 1], measuring the similarity of the
+sequences.  As a rule of thumb, a :meth:`ratio` value over 0.6 means the
+sequences are close matches::
+
+   >>> print round(s.ratio(), 3)
+   0.866
+
+If you're only interested in where the sequences match,
+:meth:`get_matching_blocks` is handy::
+
+   >>> for block in s.get_matching_blocks():
+   ...     print "a[%d] and b[%d] match for %d elements" % block
+   a[0] and b[0] match for 8 elements
+   a[8] and b[17] match for 6 elements
+   a[14] and b[23] match for 15 elements
+   a[29] and b[38] match for 0 elements
+
+Note that the last tuple returned by :meth:`get_matching_blocks` is always a
+dummy, ``(len(a), len(b), 0)``, and this is the only case in which the last
+tuple element (number of elements matched) is ``0``.
+
+If you want to know how to change the first sequence into the second, use
+:meth:`get_opcodes`::
+
+   >>> for opcode in s.get_opcodes():
+   ...     print "%6s a[%d:%d] b[%d:%d]" % opcode
+    equal a[0:8] b[0:8]
+   insert a[8:8] b[8:17]
+    equal a[8:14] b[17:23]
+    equal a[14:29] b[23:38]
+
+See also the function :func:`get_close_matches` in this module, which shows how
+simple code building on :class:`SequenceMatcher` can be used to do useful work.
+
+
+.. _differ-objects:
+
+Differ Objects
+--------------
+
+Note that :class:`Differ`\ -generated deltas make no claim to be **minimal**
+diffs. To the contrary, minimal diffs are often counter-intuitive, because they
+synch up anywhere possible, sometimes accidental matches 100 pages apart.
+Restricting synch points to contiguous matches preserves some notion of
+locality, at the occasional cost of producing a longer diff.
+
+The :class:`Differ` class has this constructor:
+
+
+.. class:: Differ([linejunk[, charjunk]])
+
+   Optional keyword parameters *linejunk* and *charjunk* are for filter functions
+   (or ``None``):
+
+   *linejunk*: A function that accepts a single string argument, and returns true
+   if the string is junk.  The default is ``None``, meaning that no line is
+   considered junk.
+
+   *charjunk*: A function that accepts a single character argument (a string of
+   length 1), and returns true if the character is junk. The default is ``None``,
+   meaning that no character is considered junk.
+
+:class:`Differ` objects are used (deltas generated) via a single method:
+
+
+.. method:: Differ.compare(a, b)
+
+   Compare two sequences of lines, and generate the delta (a sequence of lines).
+
+   Each sequence must contain individual single-line strings ending with newlines.
+   Such sequences can be obtained from the :meth:`readlines` method of file-like
+   objects.  The delta generated also consists of newline-terminated strings, ready
+   to be printed as-is via the :meth:`writelines` method of a file-like object.
+
+
+.. _differ-examples:
+
+Differ Example
+--------------
+
+This example compares two texts. First we set up the texts, sequences of
+individual single-line strings ending with newlines (such sequences can also be
+obtained from the :meth:`readlines` method of file-like objects)::
+
+   >>> text1 = '''  1. Beautiful is better than ugly.
+   ...   2. Explicit is better than implicit.
+   ...   3. Simple is better than complex.
+   ...   4. Complex is better than complicated.
+   ... '''.splitlines(1)
+   >>> len(text1)
+   4
+   >>> text1[0][-1]
+   '\n'
+   >>> text2 = '''  1. Beautiful is better than ugly.
+   ...   3.   Simple is better than complex.
+   ...   4. Complicated is better than complex.
+   ...   5. Flat is better than nested.
+   ... '''.splitlines(1)
+
+Next we instantiate a Differ object::
+
+   >>> d = Differ()
+
+Note that when instantiating a :class:`Differ` object we may pass functions to
+filter out line and character "junk."  See the :meth:`Differ` constructor for
+details.
+
+Finally, we compare the two::
+
+   >>> result = list(d.compare(text1, text2))
+
+``result`` is a list of strings, so let's pretty-print it::
+
+   >>> from pprint import pprint
+   >>> pprint(result)
+   ['    1. Beautiful is better than ugly.\n',
+    '-   2. Explicit is better than implicit.\n',
+    '-   3. Simple is better than complex.\n',
+    '+   3.   Simple is better than complex.\n',
+    '?     ++                                \n',
+    '-   4. Complex is better than complicated.\n',
+    '?            ^                     ---- ^  \n',
+    '+   4. Complicated is better than complex.\n',
+    '?           ++++ ^                      ^  \n',
+    '+   5. Flat is better than nested.\n']
+
+As a single multi-line string it looks like this::
+
+   >>> import sys
+   >>> sys.stdout.writelines(result)
+       1. Beautiful is better than ugly.
+   -   2. Explicit is better than implicit.
+   -   3. Simple is better than complex.
+   +   3.   Simple is better than complex.
+   ?     ++
+   -   4. Complex is better than complicated.
+   ?            ^                     ---- ^
+   +   4. Complicated is better than complex.
+   ?           ++++ ^                      ^
+   +   5. Flat is better than nested.
+