# Τεκμηρίωση του Django - 1.10.7

# Πηγαίος κώδικας για το django.utils.six

    """Utilities for writing code that runs on Python 2 and 3"""

    # Copyright (c) 2010-2015 Benjamin Peterson
    #
    # Permission is hereby granted, free of charge, to any person obtaining a copy
    # of this software and associated documentation files (the "Software"), to deal
    # in the Software without restriction, including without limitation the rights
    # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    # copies of the Software, and to permit persons to whom the Software is
    # furnished to do so, subject to the following conditions:
    #
    # The above copyright notice and this permission notice shall be included in all
    # copies or substantial portions of the Software.
    #
    # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    # SOFTWARE.

    from __future__ import absolute_import

    import functools
    import itertools
    import operator
    import sys
    import types

    __author__ = "Benjamin Peterson <benjamin@python.org>"
    __version__ = "1.10.0"

    # Useful for very coarse version differentiation.
    PY2 = sys.version_info[0] == 2
    PY3 = sys.version_info[0] == 3
    PY34 = sys.version_info[0:2] >= (3, 4)

    if PY3:
        string_types = str,
        integer_types = int,
        class_types = type,
        text_type = str
        binary_type = bytes

        MAXSIZE = sys.maxsize
    else:
        string_types = basestring,
        integer_types = (int, long)
        class_types = (type, types.ClassType)
        text_type = unicode
        binary_type = str

        if sys.platform.startswith("java"):
            # Jython always uses 32 bits.
            MAXSIZE = int((1 << 31) - 1)
        else:
            # It's possible to have sizeof(long) != sizeof(Py_ssize_t).
            class X(object):

                def __len__(self):
                    return 1 << 31
            try:
                len(X())
            except OverflowError:
                # 32-bit
                MAXSIZE = int((1 << 31) - 1)
            else:
                # 64-bit
                MAXSIZE = int((1 << 63) - 1)
            del X

    def _add_doc(func, doc):
        """Add documentation to a function."""
        func.__doc__ = doc

    def _import_module(name):
        """Import module, returning the module after the last dot."""
        __import__(name)
        return sys.modules[name]

    class _LazyDescr(object):

        def __init__(self, name):
            self.name = name

        def __get__(self, obj, tp):
            result = self._resolve()
            setattr(obj, self.name, result)  # Invokes __set__.
            try:
                # This is a bit ugly, but it avoids running this again by
                # removing this descriptor.
                delattr(obj.__class__, self.name)
            except AttributeError:
                pass
            return result

    class MovedModule(_LazyDescr):

        def __init__(self, name, old, new=None):
            super(MovedModule, self).__init__(name)
            if PY3:
                if new is None:
                    new = name
                self.mod = new
            else:
                self.mod = old

        def _resolve(self):
            return _import_module(self.mod)

        def __getattr__(self, attr):
            _module = self._resolve()
            value = getattr(_module, attr)
            setattr(self, attr, value)
            return value

    class _LazyModule(types.ModuleType):

        def __init__(self, name):
            super(_LazyModule, self).__init__(name)
            self.__doc__ = self.__class__.__doc__

        def __dir__(self):
            attrs = ["__doc__", "__name__"]
            attrs += [attr.name for attr in self._moved_attributes]
            return attrs

        # Subclasses should override this
        _moved_attributes = []

    class MovedAttribute(_LazyDescr):

        def __init__(self, name, old_mod, new_mod, old_attr=None, new_attr=None):
            super(MovedAttribute, self).__init__(name)
            if PY3:
                if new_mod is None:
                    new_mod = name
                self.mod = new_mod
                if new_attr is None:
                    if old_attr is None:
                        new_attr = name
                    else:
                        new_attr = old_attr
                self.attr = new_attr
            else:
                self.mod = old_mod
                if old_attr is None:
                    old_attr = name
                self.attr = old_attr

        def _resolve(self):
            module = _import_module(self.mod)
            return getattr(module, self.attr)

    class _SixMetaPathImporter(object):

        """
        A meta path importer to import six.moves and its submodules.

        This class implements a PEP302 finder and loader. It should be compatible
        with Python 2.5 and all existing versions of Python3
        """

        def __init__(self, six_module_name):
            self.name = six_module_name
            self.known_modules = {}

        def _add_module(self, mod, *fullnames):
            for fullname in fullnames:
                self.known_modules[self.name + "." + fullname] = mod

        def _get_module(self, fullname):
            return self.known_modules[self.name + "." + fullname]

        def find_module(self, fullname, path=None):
            if fullname in self.known_modules:
                return self
            return None

        def __get_module(self, fullname):
            try:
                return self.known_modules[fullname]
            except KeyError:
                raise ImportError("This loader does not know module " + fullname)

        def load_module(self, fullname):
            try:
                # in case of a reload
                return sys.modules[fullname]
            except KeyError:
                pass
            mod = self.__get_module(fullname)
            if isinstance(mod, MovedModule):
                mod = mod._resolve()
            else:
                mod.__loader__ = self
            sys.modules[fullname] = mod
            return mod

        def is_package(self, fullname):
            """
            Return true, if the named module is a package.

            We need this method to get correct spec objects with
            Python 3.4 (see PEP451)
            """
            return hasattr(self.__get_module(fullname), "__path__")

        def get_code(self, fullname):
            """Return None

            Required, if is_package is implemented"""
            self.__get_module(fullname)  # eventually raises ImportError
            return None
        get_source = get_code  # same as get_code

    _importer = _SixMetaPathImporter(__name__)

    class _MovedItems(_LazyModule):

        """Lazy loading of moved objects"""
        __path__ = []  # mark as package

    _moved_attributes = [
        MovedAttribute("cStringIO", "cStringIO", "io", "StringIO"),
        MovedAttribute("filter", "itertools", "builtins", "ifilter", "filter"),
        MovedAttribute("filterfalse", "itertools", "itertools", "ifilterfalse", "filterfalse"),
        MovedAttribute("input", "__builtin__", "builtins", "raw_input", "input"),
        MovedAttribute("intern", "__builtin__", "sys"),
        MovedAttribute("map", "itertools", "builtins", "imap", "map"),
        MovedAttribute("getcwd", "os", "os", "getcwdu", "getcwd"),
        MovedAttribute("getcwdb", "os", "os", "getcwd", "getcwdb"),
        MovedAttribute("range", "__builtin__", "builtins", "xrange", "range"),
        MovedAttribute("reload_module", "__builtin__", "importlib" if PY34 else "imp", "reload"),
        MovedAttribute("reduce", "__builtin__", "functools"),
        MovedAttribute("shlex_quote", "pipes", "shlex", "quote"),
        MovedAttribute("StringIO", "StringIO", "io"),
        MovedAttribute("UserDict", "UserDict", "collections"),
        MovedAttribute("UserList", "UserList", "collections"),
        MovedAttribute("UserString", "UserString", "collections"),
        MovedAttribute("xrange", "__builtin__", "builtins", "xrange", "range"),
        MovedAttribute("zip", "itertools", "builtins", "izip", "zip"),
        MovedAttribute("zip_longest", "itertools", "itertools", "izip_longest", "zip_longest"),
        MovedModule("builtins", "__builtin__"),
        MovedModule("configparser", "ConfigParser"),
        MovedModule("copyreg", "copy_reg"),
        MovedModule("dbm_gnu", "gdbm", "dbm.gnu"),
        MovedModule("_dummy_thread", "dummy_thread", "_dummy_thread"),
        MovedModule("http_cookiejar", "cookielib", "http.cookiejar"),
        MovedModule("http_cookies", "Cookie", "http.cookies"),
        MovedModule("html_entities", "htmlentitydefs", "html.entities"),
        MovedModule("html_parser", "HTMLParser", "html.parser"),
        MovedModule("http_client", "httplib", "http.client"),
        MovedModule("email_mime_multipart", "email.MIMEMultipart", "email.mime.multipart"),
        MovedModule("email_mime_nonmultipart", "email.MIMENonMultipart", "email.mime.nonmultipart"),
        MovedModule("email_mime_text", "email.MIMEText", "email.mime.text"),
        MovedModule("email_mime_base", "email.MIMEBase", "email.mime.base"),
        MovedModule("BaseHTTPServer", "BaseHTTPServer", "http.server"),
        MovedModule("CGIHTTPServer", "CGIHTTPServer", "http.server"),
        MovedModule("SimpleHTTPServer", "SimpleHTTPServer", "http.server"),
        MovedModule("cPickle", "cPickle", "pickle"),
        MovedModule("queue", "Queue"),
        MovedModule("reprlib", "repr"),
        MovedModule("socketserver", "SocketServer"),
        MovedModule("_thread", "thread", "_thread"),
        MovedModule("tkinter", "Tkinter"),
        MovedModule("tkinter_dialog", "Dialog", "tkinter.dialog"),
        MovedModule("tkinter_filedialog", "FileDialog", "tkinter.filedialog"),
        MovedModule("tkinter_scrolledtext", "ScrolledText", "tkinter.scrolledtext"),
        MovedModule("tkinter_simpledialog", "SimpleDialog", "tkinter.simpledialog"),
        MovedModule("tkinter_tix", "Tix", "tkinter.tix"),
        MovedModule("tkinter_ttk", "ttk", "tkinter.ttk"),
        MovedModule("tkinter_constants", "Tkconstants", "tkinter.constants"),
        MovedModule("tkinter_dnd", "Tkdnd", "tkinter.dnd"),
        MovedModule("tkinter_colorchooser", "tkColorChooser",
                    "tkinter.colorchooser"),
        MovedModule("tkinter_commondialog", "tkCommonDialog",
                    "tkinter.commondialog"),
        MovedModule("tkinter_tkfiledialog", "tkFileDialog", "tkinter.filedialog"),
        MovedModule("tkinter_font", "tkFont", "tkinter.font"),
        MovedModule("tkinter_messagebox", "tkMessageBox", "tkinter.messagebox"),
        MovedModule("tkinter_tksimpledialog", "tkSimpleDialog",
                    "tkinter.simpledialog"),
        MovedModule("urllib_parse", __name__ + ".moves.urllib_parse", "urllib.parse"),
        MovedModule("urllib_error", __name__ + ".moves.urllib_error", "urllib.error"),
        MovedModule("urllib", __name__ + ".moves.urllib", __name__ + ".moves.urllib"),
        MovedModule("urllib_robotparser", "robotparser", "urllib.robotparser"),
        MovedModule("xmlrpc_client", "xmlrpclib", "xmlrpc.client"),
        MovedModule("xmlrpc_server", "SimpleXMLRPCServer", "xmlrpc.server"),
    ]
    # Add windows specific modules.
    if sys.platform == "win32":
        _moved_attributes += [
            MovedModule("winreg", "_winreg"),
        ]

    for attr in _moved_attributes:
        setattr(_MovedItems, attr.name, attr)
        if isinstance(attr, MovedModule):
            _importer._add_module(attr, "moves." + attr.name)
    del attr

    _MovedItems._moved_attributes = _moved_attributes

    moves = _MovedItems(__name__ + ".moves")
    _importer._add_module(moves, "moves")

    class Module_six_moves_urllib_parse(_LazyModule):

        """Lazy loading of moved objects in six.moves.urllib_parse"""

    _urllib_parse_moved_attributes = [
        MovedAttribute("ParseResult", "urlparse", "urllib.parse"),
        MovedAttribute("SplitResult", "urlparse", "urllib.parse"),
        MovedAttribute("parse_qs", "urlparse", "urllib.parse"),
        MovedAttribute("parse_qsl", "urlparse", "urllib.parse"),
        MovedAttribute("urldefrag", "urlparse", "urllib.parse"),
        MovedAttribute("urljoin", "urlparse", "urllib.parse"),
        MovedAttribute("urlparse", "urlparse", "urllib.parse"),
        MovedAttribute("urlsplit", "urlparse", "urllib.parse"),
        MovedAttribute("urlunparse", "urlparse", "urllib.parse"),
        MovedAttribute("urlunsplit", "urlparse", "urllib.parse"),
        MovedAttribute("quote", "urllib", "urllib.parse"),
        MovedAttribute("quote_plus", "urllib", "urllib.parse"),
        MovedAttribute("unquote", "urllib", "urllib.parse"),
        MovedAttribute("unquote_plus", "urllib", "urllib.parse"),
        MovedAttribute("urlencode", "urllib", "urllib.parse"),
        MovedAttribute("splitquery", "urllib", "urllib.parse"),
        MovedAttribute("splittag", "urllib", "urllib.parse"),
        MovedAttribute("splituser", "urllib", "urllib.parse"),
        MovedAttribute("uses_fragment", "urlparse", "urllib.parse"),
        MovedAttribute("uses_netloc", "urlparse", "urllib.parse"),
        MovedAttribute("uses_params", "urlparse", "urllib.parse"),
        MovedAttribute("uses_query", "urlparse", "urllib.parse"),
        MovedAttribute("uses_relative", "urlparse", "urllib.parse"),
    ]
    for attr in _urllib_parse_moved_attributes:
        setattr(Module_six_moves_urllib_parse, attr.name, attr)
    del attr

    Module_six_moves_urllib_parse._moved_attributes = _urllib_parse_moved_attributes

    _importer._add_module(Module_six_moves_urllib_parse(__name__ + ".moves.urllib_parse"),
                          "moves.urllib_parse", "moves.urllib.parse")

    class Module_six_moves_urllib_error(_LazyModule):

        """Lazy loading of moved objects in six.moves.urllib_error"""

    _urllib_error_moved_attributes = [
        MovedAttribute("URLError", "urllib2", "urllib.error"),
        MovedAttribute("HTTPError", "urllib2", "urllib.error"),
        MovedAttribute("ContentTooShortError", "urllib", "urllib.error"),
    ]
    for attr in _urllib_error_moved_attributes:
        setattr(Module_six_moves_urllib_error, attr.name, attr)
    del attr

    Module_six_moves_urllib_error._moved_attributes = _urllib_error_moved_attributes

    _importer._add_module(Module_six_moves_urllib_error(__name__ + ".moves.urllib.error"),
                          "moves.urllib_error", "moves.urllib.error")

    class Module_six_moves_urllib_request(_LazyModule):

        """Lazy loading of moved objects in six.moves.urllib_request"""

    _urllib_request_moved_attributes = [
        MovedAttribute("urlopen", "urllib2", "urllib.request"),
        MovedAttribute("install_opener", "urllib2", "urllib.request"),
        MovedAttribute("build_opener", "urllib2", "urllib.request"),
        MovedAttribute("pathname2url", "urllib", "urllib.request"),
        MovedAttribute("url2pathname", "urllib", "urllib.request"),
        MovedAttribute("getproxies", "urllib", "urllib.request"),
        MovedAttribute("Request", "urllib2", "urllib.request"),
        MovedAttribute("OpenerDirector", "urllib2", "urllib.request"),
        MovedAttribute("HTTPDefaultErrorHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPRedirectHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPCookieProcessor", "urllib2", "urllib.request"),
        MovedAttribute("ProxyHandler", "urllib2", "urllib.request"),
        MovedAttribute("BaseHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPPasswordMgr", "urllib2", "urllib.request"),
        MovedAttribute("HTTPPasswordMgrWithDefaultRealm", "urllib2", "urllib.request"),
        MovedAttribute("AbstractBasicAuthHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPBasicAuthHandler", "urllib2", "urllib.request"),
        MovedAttribute("ProxyBasicAuthHandler", "urllib2", "urllib.request"),
        MovedAttribute("AbstractDigestAuthHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPDigestAuthHandler", "urllib2", "urllib.request"),
        MovedAttribute("ProxyDigestAuthHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPSHandler", "urllib2", "urllib.request"),
        MovedAttribute("FileHandler", "urllib2", "urllib.request"),
        MovedAttribute("FTPHandler", "urllib2", "urllib.request"),
        MovedAttribute("CacheFTPHandler", "urllib2", "urllib.request"),
        MovedAttribute("UnknownHandler", "urllib2", "urllib.request"),
        MovedAttribute("HTTPErrorProcessor", "urllib2", "urllib.request"),
        MovedAttribute("urlretrieve", "urllib", "urllib.request"),
        MovedAttribute("urlcleanup", "urllib", "urllib.request"),
        MovedAttribute("URLopener", "urllib", "urllib.request"),
        MovedAttribute("FancyURLopener", "urllib", "urllib.request"),
        MovedAttribute("proxy_bypass", "urllib", "urllib.request"),
    ]
    for attr in _urllib_request_moved_attributes:
        setattr(Module_six_moves_urllib_request, attr.name, attr)
    del attr

    Module_six_moves_urllib_request._moved_attributes = _urllib_request_moved_attributes

    _importer._add_module(Module_six_moves_urllib_request(__name__ + ".moves.urllib.request"),
                          "moves.urllib_request", "moves.urllib.request")

    class Module_six_moves_urllib_response(_LazyModule):

        """Lazy loading of moved objects in six.moves.urllib_response"""

    _urllib_response_moved_attributes = [
        MovedAttribute("addbase", "urllib", "urllib.response"),
        MovedAttribute("addclosehook", "urllib", "urllib.response"),
        MovedAttribute("addinfo", "urllib", "urllib.response"),
        MovedAttribute("addinfourl", "urllib", "urllib.response"),
    ]
    for attr in _urllib_response_moved_attributes:
        setattr(Module_six_moves_urllib_response, attr.name, attr)
    del attr

    Module_six_moves_urllib_response._moved_attributes = _urllib_response_moved_attributes

    _importer._add_module(Module_six_moves_urllib_response(__name__ + ".moves.urllib.response"),
                          "moves.urllib_response", "moves.urllib.response")

    class Module_six_moves_urllib_robotparser(_LazyModule):

        """Lazy loading of moved objects in six.moves.urllib_robotparser"""

    _urllib_robotparser_moved_attributes = [
        MovedAttribute("RobotFileParser", "robotparser", "urllib.robotparser"),
    ]
    for attr in _urllib_robotparser_moved_attributes:
        setattr(Module_six_moves_urllib_robotparser, attr.name, attr)
    del attr

    Module_six_moves_urllib_robotparser._moved_attributes = _urllib_robotparser_moved_attributes

    _importer._add_module(Module_six_moves_urllib_robotparser(__name__ + ".moves.urllib.robotparser"),
                          "moves.urllib_robotparser", "moves.urllib.robotparser")

    class Module_six_moves_urllib(types.ModuleType):

        """Create a six.moves.urllib namespace that resembles the Python 3 namespace"""
        __path__ = []  # mark as package
        parse = _importer._get_module("moves.urllib_parse")
        error = _importer._get_module("moves.urllib_error")
        request = _importer._get_module("moves.urllib_request")
        response = _importer._get_module("moves.urllib_response")
        robotparser = _importer._get_module("moves.urllib_robotparser")

        def __dir__(self):
            return ['parse', 'error', 'request', 'response', 'robotparser']

    _importer._add_module(Module_six_moves_urllib(__name__ + ".moves.urllib"),
                          "moves.urllib")

    def add_move(move):
        """Add an item to six.moves."""
        setattr(_MovedItems, move.name, move)

    def remove_move(name):
        """Remove item from six.moves."""
        try:
            delattr(_MovedItems, name)
        except AttributeError:
            try:
                del moves.__dict__[name]
            except KeyError:
                raise AttributeError("no such move, %r" % (name,))

    if PY3:
        _meth_func = "__func__"
        _meth_self = "__self__"

        _func_closure = "__closure__"
        _func_code = "__code__"
        _func_defaults = "__defaults__"
        _func_globals = "__globals__"
    else:
        _meth_func = "im_func"
        _meth_self = "im_self"

        _func_closure = "func_closure"
        _func_code = "func_code"
        _func_defaults = "func_defaults"
        _func_globals = "func_globals"

    try:
        advance_iterator = next
    except NameError:
        def advance_iterator(it):
            return it.next()
    next = advance_iterator

    try:
        callable = callable
    except NameError:
        def callable(obj):
            return any("__call__" in klass.__dict__ for klass in type(obj).__mro__)

    if PY3:
        def get_unbound_function(unbound):
            return unbound

        create_bound_method = types.MethodType

        def create_unbound_method(func, cls):
            return func

        Iterator = object
    else:
        def get_unbound_function(unbound):
            return unbound.im_func

        def create_bound_method(func, obj):
            return types.MethodType(func, obj, obj.__class__)

        def create_unbound_method(func, cls):
            return types.MethodType(func, None, cls)

        class Iterator(object):

            def next(self):
                return type(self).__next__(self)

        callable = callable
    _add_doc(get_unbound_function,
             """Get the function out of a possibly unbound function""")

    get_method_function = operator.attrgetter(_meth_func)
    get_method_self = operator.attrgetter(_meth_self)
    get_function_closure = operator.attrgetter(_func_closure)
    get_function_code = operator.attrgetter(_func_code)
    get_function_defaults = operator.attrgetter(_func_defaults)
    get_function_globals = operator.attrgetter(_func_globals)

    if PY3:
        def iterkeys(d, **kw):
            return iter(d.keys(**kw))

        def itervalues(d, **kw):
            return iter(d.values(**kw))

        def iteritems(d, **kw):
            return iter(d.items(**kw))

        def iterlists(d, **kw):
            return iter(d.lists(**kw))

        viewkeys = operator.methodcaller("keys")

        viewvalues = operator.methodcaller("values")

        viewitems = operator.methodcaller("items")
    else:
        def iterkeys(d, **kw):
            return d.iterkeys(**kw)

        def itervalues(d, **kw):
            return d.itervalues(**kw)

        def iteritems(d, **kw):
            return d.iteritems(**kw)

        def iterlists(d, **kw):
            return d.iterlists(**kw)

        viewkeys = operator.methodcaller("viewkeys")

        viewvalues = operator.methodcaller("viewvalues")

        viewitems = operator.methodcaller("viewitems")

    _add_doc(iterkeys, "Return an iterator over the keys of a dictionary.")
    _add_doc(itervalues, "Return an iterator over the values of a dictionary.")
    _add_doc(iteritems,
             "Return an iterator over the (key, value) pairs of a dictionary.")
    _add_doc(iterlists,
             "Return an iterator over the (key, [values]) pairs of a dictionary.")

    if PY3:
        def b(s):
            return s.encode("latin-1")

        def u(s):
            return s
        unichr = chr
        import struct
        int2byte = struct.Struct(">B").pack
        del struct
        byte2int = operator.itemgetter(0)
        indexbytes = operator.getitem
        iterbytes = iter
        import io
        StringIO = io.StringIO
        BytesIO = io.BytesIO
        _assertCountEqual = "assertCountEqual"
        if sys.version_info[1] <= 1:
            _assertRaisesRegex = "assertRaisesRegexp"
            _assertRegex = "assertRegexpMatches"
        else:
            _assertRaisesRegex = "assertRaisesRegex"
            _assertRegex = "assertRegex"
    else:
        def b(s):
            return s
        # Workaround for standalone backslash

        def u(s):
            return unicode(s.replace(r'\\', r'\\\\'), "unicode_escape")
        unichr = unichr
        int2byte = chr

        def byte2int(bs):
            return ord(bs[0])

        def indexbytes(buf, i):
            return ord(buf[i])
        iterbytes = functools.partial(itertools.imap, ord)
        import StringIO
        StringIO = BytesIO = StringIO.StringIO
        _assertCountEqual = "assertItemsEqual"
        _assertRaisesRegex = "assertRaisesRegexp"
        _assertRegex = "assertRegexpMatches"
    _add_doc(b, """Byte literal""")
    _add_doc(u, """Text literal""")

    def assertCountEqual(self, *args, **kwargs):
        return getattr(self, _assertCountEqual)(*args, **kwargs)

    def assertRaisesRegex(self, *args, **kwargs):
        return getattr(self, _assertRaisesRegex)(*args, **kwargs)

    def assertRegex(self, *args, **kwargs):
        return getattr(self, _assertRegex)(*args, **kwargs)

    if PY3:
        exec_ = getattr(moves.builtins, "exec")

        def reraise(tp, value, tb=None):
            if value is None:
                value = tp()
            if value.__traceback__ is not tb:
                raise value.with_traceback(tb)
            raise value

    else:
        def exec_(_code_, _globs_=None, _locs_=None):
            """Execute code in a namespace."""
            if _globs_ is None:
                frame = sys._getframe(1)
                _globs_ = frame.f_globals
                if _locs_ is None:
                    _locs_ = frame.f_locals
                del frame
            elif _locs_ is None:
                _locs_ = _globs_
            exec("""exec _code_ in _globs_, _locs_""")

        exec_("""def reraise(tp, value, tb=None):
        raise tp, value, tb
    """)

    if sys.version_info[:2] == (3, 2):
        exec_("""def raise_from(value, from_value):
        if from_value is None:
            raise value
        raise value from from_value
    """)
    elif sys.version_info[:2] > (3, 2):
        exec_("""def raise_from(value, from_value):
        raise value from from_value
    """)
    else:
        def raise_from(value, from_value):
            raise value

    print_ = getattr(moves.builtins, "print", None)
    if print_ is None:
        def print_(*args, **kwargs):
            """The new-style print function for Python 2.4 and 2.5."""
            fp = kwargs.pop("file", sys.stdout)
            if fp is None:
                return

            def write(data):
                if not isinstance(data, basestring):
                    data = str(data)
                # If the file has an encoding, encode unicode with it.
                if (isinstance(fp, file) and
                        isinstance(data, unicode) and
                        fp.encoding is not None):
                    errors = getattr(fp, "errors", None)
                    if errors is None:
                        errors = "strict"
                    data = data.encode(fp.encoding, errors)
                fp.write(data)
            want_unicode = False
            sep = kwargs.pop("sep", None)
            if sep is not None:
                if isinstance(sep, unicode):
                    want_unicode = True
                elif not isinstance(sep, str):
                    raise TypeError("sep must be None or a string")
            end = kwargs.pop("end", None)
            if end is not None:
                if isinstance(end, unicode):
                    want_unicode = True
                elif not isinstance(end, str):
                    raise TypeError("end must be None or a string")
            if kwargs:
                raise TypeError("invalid keyword arguments to print()")
            if not want_unicode:
                for arg in args:
                    if isinstance(arg, unicode):
                        want_unicode = True
                        break
            if want_unicode:
                newline = unicode("\n")
                space = unicode(" ")
            else:
                newline = "\n"
                space = " "
            if sep is None:
                sep = space
            if end is None:
                end = newline
            for i, arg in enumerate(args):
                if i:
                    write(sep)
                write(arg)
            write(end)
    if sys.version_info[:2] < (3, 3):
        _print = print_

        def print_(*args, **kwargs):
            fp = kwargs.get("file", sys.stdout)
            flush = kwargs.pop("flush", False)
            _print(*args, **kwargs)
            if flush and fp is not None:
                fp.flush()

    _add_doc(reraise, """Reraise an exception.""")

    if sys.version_info[0:2] < (3, 4):
        def wraps(wrapped, assigned=functools.WRAPPER_ASSIGNMENTS,
                  updated=functools.WRAPPER_UPDATES):
            def wrapper(f):
                f = functools.wraps(wrapped, assigned, updated)(f)
                f.__wrapped__ = wrapped
                return f
            return wrapper
    else:
        wraps = functools.wraps

    def with_metaclass(meta, *bases):
        """Create a base class with a metaclass."""
        # This requires a bit of explanation: the basic idea is to make a dummy
        # metaclass for one level of class instantiation that replaces itself with
        # the actual metaclass.
        class metaclass(meta):

            def __new__(cls, name, this_bases, d):
                return meta(name, bases, d)
        return type.__new__(metaclass, 'temporary_class', (), {})

    def add_metaclass(metaclass):
        """Class decorator for creating a class with a metaclass."""
        def wrapper(cls):
            orig_vars = cls.__dict__.copy()
            slots = orig_vars.get('__slots__')
            if slots is not None:
                if isinstance(slots, str):
                    slots = [slots]
                for slots_var in slots:
                    orig_vars.pop(slots_var)
            orig_vars.pop('__dict__', None)
            orig_vars.pop('__weakref__', None)
            return metaclass(cls.__name__, cls.__bases__, orig_vars)
        return wrapper

    def python_2_unicode_compatible(klass):
        """
        A decorator that defines __unicode__ and __str__ methods under Python 2.
        Under Python 3 it does nothing.

        To support Python 2 and 3 with a single code base, define a __str__ method
        returning text and apply this decorator to the class.
        """
        if PY2:
            if '__str__' not in klass.__dict__:
                raise ValueError("@python_2_unicode_compatible cannot be applied "
                                 "to %s because it doesn't define __str__()." %
                                 klass.__name__)
            klass.__unicode__ = klass.__str__
            klass.__str__ = lambda self: self.__unicode__().encode('utf-8')
        return klass

    # Complete the moves implementation.
    # This code is at the end of this module to speed up module loading.
    # Turn this module into a package.
    __path__ = []  # required for PEP 302 and PEP 451
    __package__ = __name__  # see PEP 366 @ReservedAssignment
    if globals().get("__spec__") is not None:
        __spec__.submodule_search_locations = []  # PEP 451 @UndefinedVariable
    # Remove other six meta path importers, since they cause problems. This can
    # happen if six is removed from sys.modules and then reloaded. (Setuptools does
    # this for some reason.)
    if sys.meta_path:
        for i, importer in enumerate(sys.meta_path):
            # Here's some real nastiness: Another "instance" of the six module might
            # be floating around. Therefore, we can't use isinstance() to check for
            # the six meta path importer, since the other six instance will have
            # inserted an importer with different class.
            if (type(importer).__name__ == "_SixMetaPathImporter" and
                    importer.name == __name__):
                del sys.meta_path[i]
                break
        del i, importer
    # Finally, add the importer to the meta path import hook.
    sys.meta_path.append(_importer)

    ### Additional customizations for Django ###

    if PY3:
        memoryview = memoryview
        buffer_types = (bytes, bytearray, memoryview)
    else:
        # memoryview and buffer are not strictly equivalent, but should be fine for
        # django core usage (mainly BinaryField). However, Jython doesn't support
        # buffer (see http://bugs.jython.org/issue1521), so we have to be careful.
        if sys.platform.startswith('java'):
            memoryview = memoryview
        else:
            memoryview = buffer
        buffer_types = (bytearray, memoryview)