Issue #25523: Merge a-to-an corrections from 3.4.

34 files changed, 39 insertions, 39 deletions

diff --git a/Doc/distutils/packageindex.rst b/Doc/distutils/packageindex.rst
index daf9345..2d7daef 100644
--- a/Doc/distutils/packageindex.rst
+++ b/Doc/distutils/packageindex.rst
@@ -167,7 +167,7 @@ follows::
     username: <username>
     password: <password>
 
-The *distutils* section defines a *index-servers* variable that lists the
+The *distutils* section defines an *index-servers* variable that lists the
 name of all sections describing a repository.
 
 Each section describing a repository defines three variables:
diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index f018b0e..530f34b 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -319,7 +319,7 @@ Non-data descriptors provide a simple mechanism for variations on the usual
 patterns of binding functions into methods.
 
 To recap, functions have a :meth:`__get__` method so that they can be converted
-to a method when accessed as attributes.  The non-data descriptor transforms a
+to a method when accessed as attributes.  The non-data descriptor transforms an
 ``obj.f(*args)`` call into ``f(obj, *args)``.  Calling ``klass.f(*args)``
 becomes ``f(*args)``.
 
diff --git a/Doc/install/index.rst b/Doc/install/index.rst
index 876f350..2ea047a 100644
--- a/Doc/install/index.rst
+++ b/Doc/install/index.rst
@@ -148,7 +148,7 @@ into.  For example, if you've just downloaded a module source distribution
 
 On Windows, you'd probably download :file:`foo-1.0.zip`.  If you downloaded the
 archive file to :file:`C:\\Temp`, then it would unpack into
-:file:`C:\\Temp\\foo-1.0`; you can use either a archive manipulator with a
+:file:`C:\\Temp\\foo-1.0`; you can use either an archive manipulator with a
 graphical user interface (such as WinZip) or a command-line tool (such as
 :program:`unzip` or :program:`pkunzip`) to unpack the archive.  Then, open a
 command prompt window and run::
diff --git a/Doc/library/asyncio-protocol.rst b/Doc/library/asyncio-protocol.rst
index 93694f3..9264343 100644
--- a/Doc/library/asyncio-protocol.rst
+++ b/Doc/library/asyncio-protocol.rst
@@ -148,7 +148,7 @@ WriteTransport
       high-water limit.  Neither *high* nor *low* can be negative.
 
       The defaults are implementation-specific.  If only the
-      high-water limit is given, the low-water limit defaults to a
+      high-water limit is given, the low-water limit defaults to an
       implementation-specific value less than or equal to the
       high-water limit.  Setting *high* to zero forces *low* to zero as
       well, and causes :meth:`pause_writing` to be called whenever the
diff --git a/Doc/library/contextlib.rst b/Doc/library/contextlib.rst
index 38f3782..9e8463d 100644
--- a/Doc/library/contextlib.rst
+++ b/Doc/library/contextlib.rst
@@ -142,7 +142,7 @@ Functions and classes provided:
    is hardwired to stdout.
 
    For example, the output of :func:`help` normally is sent to *sys.stdout*.
-   You can capture that output in a string by redirecting the output to a
+   You can capture that output in a string by redirecting the output to an
    :class:`io.StringIO` object::
 
         f = io.StringIO()
diff --git a/Doc/library/email.parser.rst b/Doc/library/email.parser.rst
index ec74fe0..177adc6 100644
--- a/Doc/library/email.parser.rst
+++ b/Doc/library/email.parser.rst
@@ -146,7 +146,7 @@ have the same API as the :class:`Parser` and :class:`BytesParser` classes.
       methods on file-like objects.
 
       The text contained in *fp* must be formatted as a block of :rfc:`2822`
-      style headers and header continuation lines, optionally preceded by a
+      style headers and header continuation lines, optionally preceded by an
       envelope header.  The header block is terminated either by the end of the
       data or by a blank line.  Following the header block is the body of the
       message (which may contain MIME-encoded subparts).
@@ -189,7 +189,7 @@ have the same API as the :class:`Parser` and :class:`BytesParser` classes.
       methods on file-like objects.
 
       The bytes contained in *fp* must be formatted as a block of :rfc:`2822`
-      style headers and header continuation lines, optionally preceded by a
+      style headers and header continuation lines, optionally preceded by an
       envelope header.  The header block is terminated either by the end of the
       data or by a blank line.  Following the header block is the body of the
       message (which may contain MIME-encoded subparts, including subparts
diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst
index 9492716..792d57a 100644
--- a/Doc/library/gzip.rst
+++ b/Doc/library/gzip.rst
@@ -64,7 +64,7 @@ The module defines the following items:
    method.  At least one of *fileobj* and *filename* must be given a non-trivial
    value.
 
-   The new class instance is based on *fileobj*, which can be a regular file, a
+   The new class instance is based on *fileobj*, which can be a regular file, an
    :class:`io.BytesIO` object, or any other object which simulates a file.  It
    defaults to ``None``, in which case *filename* is opened to provide a file
    object.
diff --git a/Doc/library/pickle.rst b/Doc/library/pickle.rst
index 36b43b4..7e09b03 100644
--- a/Doc/library/pickle.rst
+++ b/Doc/library/pickle.rst
@@ -192,7 +192,7 @@ process more convenient:
    number is specified, :data:`HIGHEST_PROTOCOL` is selected.
 
    The *file* argument must have a write() method that accepts a single bytes
-   argument.  It can thus be an on-disk file opened for binary writing, a
+   argument.  It can thus be an on-disk file opened for binary writing, an
    :class:`io.BytesIO` instance, or any other custom object that meets this
    interface.
 
@@ -288,7 +288,7 @@ The :mod:`pickle` module exports two classes, :class:`Pickler` and
    number is specified, :data:`HIGHEST_PROTOCOL` is selected.
 
    The *file* argument must have a write() method that accepts a single bytes
-   argument.  It can thus be an on-disk file opened for binary writing, a
+   argument.  It can thus be an on-disk file opened for binary writing, an
    :class:`io.BytesIO` instance, or any other custom object that meets this
    interface.
 
diff --git a/Doc/library/socket.rst b/Doc/library/socket.rst
index 2579b0b..a081756 100644
--- a/Doc/library/socket.rst
+++ b/Doc/library/socket.rst
@@ -786,7 +786,7 @@ The :mod:`socket` module also offers various network-related services:
 
 .. function:: sethostname(name)
 
-   Set the machine's hostname to *name*.  This will raise a
+   Set the machine's hostname to *name*.  This will raise an
    :exc:`OSError` if you don't have enough rights.
 
    Availability: Unix.
@@ -818,7 +818,7 @@ The :mod:`socket` module also offers various network-related services:
 
 .. function:: if_indextoname(if_index)
 
-   Return a network interface name corresponding to a
+   Return a network interface name corresponding to an
    interface index number.
    :exc:`OSError` if no interface with the given index exists.
 
diff --git a/Doc/library/tokenize.rst b/Doc/library/tokenize.rst
index bd6b121..c9cb518 100644
--- a/Doc/library/tokenize.rst
+++ b/Doc/library/tokenize.rst
@@ -41,7 +41,7 @@ The primary entry point is a :term:`generator`:
    returned as a :term:`named tuple` with the field names:
    ``type string start end line``.
 
-   The returned :term:`named tuple` has a additional property named
+   The returned :term:`named tuple` has an additional property named
    ``exact_type`` that contains the exact operator type for
    :data:`token.OP` tokens.  For all other token types ``exact_type``
    equals the named tuple ``type`` field.
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index d3a3649..ff9cc22 100644
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -471,7 +471,7 @@ Skipping tests and expected failures
 .. versionadded:: 3.1
 
 Unittest supports skipping individual test methods and even whole classes of
-tests.  In addition, it supports marking a test as a "expected failure," a test
+tests.  In addition, it supports marking a test as an "expected failure," a test
 that is broken and will fail, but shouldn't be counted as a failure on a
 :class:`TestResult`.
 
diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst
index 18df078..81aeb12 100644
--- a/Doc/library/urllib.request.rst
+++ b/Doc/library/urllib.request.rst
@@ -1383,7 +1383,7 @@ some point in the future.
     .. method:: retrieve(url, filename=None, reporthook=None, data=None)
 
        Retrieves the contents of *url* and places it in *filename*.  The return value
-       is a tuple consisting of a local filename and either a
+       is a tuple consisting of a local filename and either an
        :class:`email.message.Message` object containing the response headers (for remote
        URLs) or ``None`` (for local URLs).  The caller must then open and read the
        contents of *filename*.  If *filename* is not given and the URL refers to a
diff --git a/Doc/library/xml.dom.minidom.rst b/Doc/library/xml.dom.minidom.rst
index dcd030c..6762e91 100644
--- a/Doc/library/xml.dom.minidom.rst
+++ b/Doc/library/xml.dom.minidom.rst
@@ -54,7 +54,7 @@ instead:
 
 .. function:: parseString(string, parser=None)
 
-   Return a :class:`Document` that represents the *string*. This method creates a
+   Return a :class:`Document` that represents the *string*. This method creates an
    :class:`io.StringIO` object for the string and passes that on to :func:`parse`.
 
 Both functions return a :class:`Document` object representing the content of the
diff --git a/Doc/library/zlib.rst b/Doc/library/zlib.rst
index aea0e79..230fdfe 100644
--- a/Doc/library/zlib.rst
+++ b/Doc/library/zlib.rst
@@ -30,7 +30,7 @@ The available exception and functions in this module are:
 
 .. function:: adler32(data[, value])
 
-   Computes a Adler-32 checksum of *data*.  (An Adler-32 checksum is almost as
+   Computes an Adler-32 checksum of *data*.  (An Adler-32 checksum is almost as
    reliable as a CRC32 but can be computed much more quickly.)  If *value* is
    present, it is used as the starting value of the checksum; otherwise, a fixed
    default value is used.  This allows computing a running checksum over the
diff --git a/Doc/whatsnew/2.7.rst b/Doc/whatsnew/2.7.rst
index fb0551e..3966cb4 100644
--- a/Doc/whatsnew/2.7.rst
+++ b/Doc/whatsnew/2.7.rst
@@ -1118,7 +1118,7 @@ changes, or look through the Subversion logs for all the details.
   (Fixed by Daniel Stutzbach; :issue:`8729`.)
 
 * Constructors for the parsing classes in the :mod:`ConfigParser` module now
-  take a *allow_no_value* parameter, defaulting to false; if true,
+  take an *allow_no_value* parameter, defaulting to false; if true,
   options without values will be allowed.  For example::
 
     >>> import ConfigParser, StringIO
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index 48379d9..094eff8 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -2155,7 +2155,7 @@ Major performance enhancements have been added:
   * encode an ASCII string to UTF-8 doesn't need to encode characters anymore,
     the UTF-8 representation is shared with the ASCII representation
   * the UTF-8 encoder has been optimized
-  * repeating a single ASCII letter and getting a substring of a ASCII strings
+  * repeating a single ASCII letter and getting a substring of an ASCII string
     is 4 times faster
 
 * UTF-8 is now 2x to 4x faster.  UTF-16 encoding is now up to 10x faster.
diff --git a/Include/unicodeobject.h b/Include/unicodeobject.h
index 4ba6328..09c9b21 100644
--- a/Include/unicodeobject.h
+++ b/Include/unicodeobject.h
@@ -965,7 +965,7 @@ _PyUnicodeWriter_WriteSubstring(_PyUnicodeWriter *writer,
     Py_ssize_t end
     );
 
-/* Append a ASCII-encoded byte string.
+/* Append an ASCII-encoded byte string.
    Return 0 on success, raise an exception and return -1 on error. */
 PyAPI_FUNC(int)
 _PyUnicodeWriter_WriteASCIIString(_PyUnicodeWriter *writer,
@@ -2041,7 +2041,7 @@ PyAPI_FUNC(PyObject *) PyUnicode_RichCompare(
     int op                      /* Operation: Py_EQ, Py_NE, Py_GT, etc. */
     );
 
-/* Apply a argument tuple or dictionary to a format string and return
+/* Apply an argument tuple or dictionary to a format string and return
    the resulting Unicode string. */
 
 PyAPI_FUNC(PyObject *) PyUnicode_Format(
diff --git a/Lib/asyncio/sslproto.py b/Lib/asyncio/sslproto.py
index 0a8c090..9e08b6f 100644
--- a/Lib/asyncio/sslproto.py
+++ b/Lib/asyncio/sslproto.py
@@ -349,7 +349,7 @@ class _SSLProtocolTransport(transports._FlowControlMixin,
         high-water limit.  Neither value can be negative.
 
         The defaults are implementation-specific.  If only the
-        high-water limit is given, the low-water limit defaults to a
+        high-water limit is given, the low-water limit defaults to an
         implementation-specific value less than or equal to the
         high-water limit.  Setting high to zero forces low to zero as
         well, and causes pause_writing() to be called whenever the
diff --git a/Lib/asyncio/transports.py b/Lib/asyncio/transports.py
index 70b323f..03099e3 100644
--- a/Lib/asyncio/transports.py
+++ b/Lib/asyncio/transports.py
@@ -62,7 +62,7 @@ class WriteTransport(BaseTransport):
         high-water limit.  Neither value can be negative.
 
         The defaults are implementation-specific.  If only the
-        high-water limit is given, the low-water limit defaults to a
+        high-water limit is given, the low-water limit defaults to an
         implementation-specific value less than or equal to the
         high-water limit.  Setting high to zero forces low to zero as
         well, and causes pause_writing() to be called whenever the
diff --git a/Lib/ctypes/test/test_random_things.py b/Lib/ctypes/test/test_random_things.py
index 4555ecd..ee5b212 100644
--- a/Lib/ctypes/test/test_random_things.py
+++ b/Lib/ctypes/test/test_random_things.py
@@ -30,7 +30,7 @@ class CallbackTracbackTestCase(unittest.TestCase):
     # value is printed correctly.
     #
     # Changed in 0.9.3: No longer is '(in callback)' prepended to the
-    # error message - instead a additional frame for the C code is
+    # error message - instead an additional frame for the C code is
     # created, then a full traceback printed.  When SystemExit is
     # raised in a callback function, the interpreter exits.
 
diff --git a/Lib/http/cookiejar.py b/Lib/http/cookiejar.py
index b1ba72e..e215398 100644
--- a/Lib/http/cookiejar.py
+++ b/Lib/http/cookiejar.py
@@ -1437,7 +1437,7 @@ class CookieJar:
                         break
                     # convert RFC 2965 Max-Age to seconds since epoch
                     # XXX Strictly you're supposed to follow RFC 2616
-                    #   age-calculation rules.  Remember that zero Max-Age is a
+                    #   age-calculation rules.  Remember that zero Max-Age
                     #   is a request to discard (old and new) cookie, though.
                     k = "expires"
                     v = self._now + v
diff --git a/Lib/lib2to3/fixes/fix_metaclass.py b/Lib/lib2to3/fixes/fix_metaclass.py
index d4f99a3..f3f8708 100644
--- a/Lib/lib2to3/fixes/fix_metaclass.py
+++ b/Lib/lib2to3/fixes/fix_metaclass.py
@@ -114,7 +114,7 @@ def find_metas(cls_node):
                 left_node = expr_node.children[0]
                 if isinstance(left_node, Leaf) and \
                         left_node.value == '__metaclass__':
-                    # We found a assignment to __metaclass__.
+                    # We found an assignment to __metaclass__.
                     fixup_simple_stmt(node, i, simple_node)
                     remove_trailing_newline(simple_node)
                     yield (node, i, simple_node)
diff --git a/Lib/msilib/schema.py b/Lib/msilib/schema.py
index a9e1679..70fe138 100644
--- a/Lib/msilib/schema.py
+++ b/Lib/msilib/schema.py
@@ -733,7 +733,7 @@ _Validation_records = [
 ('CustomAction','Source','Y',None, None, None, None, 'CustomSource',None, 'The table reference of the source of the code.',),
 ('CustomAction','Target','Y',None, None, None, None, 'Formatted',None, 'Excecution parameter, depends on the type of custom action',),
 ('DrLocator','Signature_','N',None, None, None, None, 'Identifier',None, 'The Signature_ represents a unique file signature and is also the foreign key in the Signature table.',),
-('DrLocator','Path','Y',None, None, None, None, 'AnyPath',None, 'The path on the user system. This is a either a subpath below the value of the Parent or a full path. The path may contain properties enclosed within [ ] that will be expanded.',),
+('DrLocator','Path','Y',None, None, None, None, 'AnyPath',None, 'The path on the user system. This is either a subpath below the value of the Parent or a full path. The path may contain properties enclosed within [ ] that will be expanded.',),
 ('DrLocator','Depth','Y',0,32767,None, None, None, None, 'The depth below the path to which the Signature_ is recursively searched. If absent, the depth is assumed to be 0.',),
 ('DrLocator','Parent','Y',None, None, None, None, 'Identifier',None, 'The parent file signature. It is also a foreign key in the Signature table. If null and the Path column does not expand to a full path, then all the fixed drives of the user system are searched using the Path.',),
 ('DuplicateFile','File_','N',None, None, 'File',1,'Identifier',None, 'Foreign key referencing the source file to be duplicated.',),
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index dedfdfe..431042e 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -27,7 +27,7 @@ python -E -Wd -m test [options] [test_name1 ...]
 EPILOG = """\
 Additional option details:
 
--r randomizes test execution order. You can use --randseed=int to provide a
+-r randomizes test execution order. You can use --randseed=int to provide an
 int seed value for the randomizer; this is useful for reproducing troublesome
 test orders.
 
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index 2488b63..3b42414 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -603,7 +603,7 @@ class DictTest(unittest.TestCase):
         # (D) subclass defines __missing__ method returning a value
         # (E) subclass defines __missing__ method raising RuntimeError
         # (F) subclass sets __missing__ instance variable (no effect)
-        # (G) subclass doesn't define __missing__ at a all
+        # (G) subclass doesn't define __missing__ at all
         class D(dict):
             def __missing__(self, key):
                 return 42
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 465d45a..28f440d 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -15,7 +15,7 @@
 ################################################################################
 # When writing tests for io, it's important to test both the C and Python
 # implementations. This is usually done by writing a base test that refers to
-# the type it is testing as a attribute. Then it provides custom subclasses to
+# the type it is testing as an attribute. Then it provides custom subclasses to
 # test both implementations. This file has lots of examples.
 ################################################################################
 
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 63cc284..1e355ea 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -4549,7 +4549,7 @@ class TestUnixDomain(unittest.TestCase):
         except OSError as e:
             if str(e) == "AF_UNIX path too long":
                 self.skipTest(
-                    "Pathname {0!a} is too long to serve as a AF_UNIX path"
+                    "Pathname {0!a} is too long to serve as an AF_UNIX path"
                     .format(path))
             else:
                 raise
diff --git a/Lib/test/test_userdict.py b/Lib/test/test_userdict.py
index 68a582c..1288943 100644
--- a/Lib/test/test_userdict.py
+++ b/Lib/test/test_userdict.py
@@ -171,7 +171,7 @@ class UserDictTest(mapping_tests.TestHashMappingProtocol):
         # (D) subclass defines __missing__ method returning a value
         # (E) subclass defines __missing__ method raising RuntimeError
         # (F) subclass sets __missing__ instance variable (no effect)
-        # (G) subclass doesn't define __missing__ at a all
+        # (G) subclass doesn't define __missing__ at all
         class D(collections.UserDict):
             def __missing__(self, key):
                 return 42
diff --git a/Lib/tkinter/__init__.py b/Lib/tkinter/__init__.py
index ea747ac..12085a9 100644
--- a/Lib/tkinter/__init__.py
+++ b/Lib/tkinter/__init__.py
@@ -1123,7 +1123,7 @@ class Misc:
 
         return self._bind(('bind', className), sequence, func, add, 0)
     def unbind_class(self, className, sequence):
-        """Unbind for a all widgets with bindtag CLASSNAME for event SEQUENCE
+        """Unbind for all widgets with bindtag CLASSNAME for event SEQUENCE
         all functions."""
         self.tk.call('bind', className , sequence, '')
     def mainloop(self, n=0):
diff --git a/Misc/HISTORY b/Misc/HISTORY
index 24cb69f..5e5bc60 100644
--- a/Misc/HISTORY
+++ b/Misc/HISTORY
@@ -12412,7 +12412,7 @@ Extension Modules
 
 - Bug #1194181: bz2.BZ2File didn't handle mode 'U' correctly.
 
-- Patch #1212117: os.stat().st_flags is now accessible as a attribute
+- Patch #1212117: os.stat().st_flags is now accessible as an attribute
   if available on the platform.
 
 - Patch #1103951: Expose O_SHLOCK and O_EXLOCK in the posix module if
diff --git a/Misc/NEWS b/Misc/NEWS
index f40fc41..5fb54d8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -3072,7 +3072,7 @@ IDLE
   Changes are written to HOME/.idlerc/config-extensions.cfg.
   Original patch by Tal Einat.
 
-- Issue #16233: A module browser (File : Class Browser, Alt+C) requires a
+- Issue #16233: A module browser (File : Class Browser, Alt+C) requires an
   editor window with a filename.  When Class Browser is requested otherwise,
   from a shell, output window, or 'Untitled' editor, Idle no longer displays
   an error box.  It now pops up an Open Module box (Alt+M). If a valid name
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index e43c502..5d20e7c 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -2996,7 +2996,7 @@ _ssl__SSLContext_load_verify_locations_impl(PySSLContext *self,
             cadata_ascii = PyUnicode_AsASCIIString(cadata);
             if (cadata_ascii == NULL) {
                 PyErr_SetString(PyExc_TypeError,
-                                "cadata should be a ASCII string or a "
+                                "cadata should be an ASCII string or a "
                                 "bytes-like object");
                 goto error;
             }
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index 16ac2fb..dfafeab 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -1725,7 +1725,7 @@ PyDoc_STRVAR(starmap_doc,
 "starmap(function, sequence) --> starmap object\n\
 \n\
 Return an iterator whose values are returned from the function evaluated\n\
-with a argument tuple taken from the given sequence.");
+with an argument tuple taken from the given sequence.");
 
 static PyTypeObject starmap_type = {
     PyVarObject_HEAD_INIT(NULL, 0)
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 168f9f9..38f765d 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -1701,7 +1701,7 @@ PyUnicode_Resize(PyObject **p_unicode, Py_ssize_t length)
     return unicode_resize(p_unicode, length);
 }
 
-/* Copy a ASCII or latin1 char* string into a Python Unicode string.
+/* Copy an ASCII or latin1 char* string into a Python Unicode string.
 
    WARNING: The function doesn't copy the terminating null character and
    doesn't check the maximum character (may write a latin1 character in an
@@ -7191,7 +7191,7 @@ error:
 }
 
 /*
- * Encode a Unicode string to a Windows code page into a byte string using a
+ * Encode a Unicode string to a Windows code page into a byte string using an
  * error handler.
  *
  * Returns consumed characters if succeed, or raise an OSError and returns