Update Six compatibility library 1.5.2 to 1.9.0 (8a545f4).

CHANGES.md

@@ -39,6 +39,7 @@
 * Change Kodi notifier to use requests as opposed to urllib
 * Change to consolidate scene exceptions and name cache code
 * Change check_url function to use requests instead of httplib library
+* Update Six compatibility library 1.5.2 to 1.9.0 (8a545f4)
 
 [develop changelog]
 * Update Requests library 2.7.0 (ab1f493) to 2.7.0 (8b5e457)

lib/six.py

@@ -1,6 +1,6 @@
 """Utilities for writing code that runs on Python 2 and 3"""
 
-# Copyright (c) 2010-2014 Benjamin Peterson
+# 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
@@ -20,17 +20,22 @@
 # 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__ = "1.5.2"
+__version__ = "1.9.0"
 
 
 # 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,
@@ -53,6 +58,7 @@ else:
     else:
         # It's possible to have sizeof(long) != sizeof(Py_ssize_t).
         class X(object):
+
             def __len__(self):
                 return 1 << 31
         try:
@@ -85,8 +91,12 @@ class _LazyDescr(object):
     def __get__(self, obj, tp):
         result = self._resolve()
         setattr(obj, self.name, result)  # Invokes __set__.
-        # This is a bit ugly, but it avoids running this again.
+        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
 
 
@@ -105,14 +115,6 @@ class MovedModule(_LazyDescr):
         return _import_module(self.mod)
 
     def __getattr__(self, attr):
-        # Hack around the Django autoreloader. The reloader tries to get
-        # __file__ or __name__ of every module in sys.modules. This doesn't work
-        # well if this MovedModule is for an module that is unavailable on this
-        # machine (like winreg on Unix systems). Thus, we pretend __file__ and
-        # __name__ don't exist if the module hasn't been loaded yet. See issues
-        # #51 and #53.
-        if attr in ("__file__", "__name__") and self.mod not in sys.modules:
-            raise AttributeError
         _module = self._resolve()
         value = getattr(_module, attr)
         setattr(self, attr, value)
@@ -159,9 +161,75 @@ class MovedAttribute(_LazyDescr):
         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 = [
@@ -169,26 +237,33 @@ _moved_attributes = [
     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__", "imp", "reload"),
+    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"),
@@ -222,25 +297,34 @@ _moved_attributes = [
     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):
-        sys.modules[__name__ + ".moves." + attr.name] = attr
+        _importer._add_module(attr, "moves." + attr.name)
 del attr
 
 _MovedItems._moved_attributes = _moved_attributes
 
-moves = sys.modules[__name__ + ".moves"] = _MovedItems(__name__ + ".moves")
+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"),
@@ -254,6 +338,14 @@ _urllib_parse_moved_attributes = [
     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)
@@ -261,10 +353,12 @@ del attr
 
 Module_six_moves_urllib_parse._moved_attributes = _urllib_parse_moved_attributes
 
-sys.modules[__name__ + ".moves.urllib_parse"] = sys.modules[__name__ + ".moves.urllib.parse"] = Module_six_moves_urllib_parse(__name__ + ".moves.urllib_parse")
+_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"""
 
 
@@ -279,10 +373,12 @@ del attr
 
 Module_six_moves_urllib_error._moved_attributes = _urllib_error_moved_attributes
 
-sys.modules[__name__ + ".moves.urllib_error"] = sys.modules[__name__ + ".moves.urllib.error"] = Module_six_moves_urllib_error(__name__ + ".moves.urllib.error")
+_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"""
 
 
@@ -327,10 +423,12 @@ del attr
 
 Module_six_moves_urllib_request._moved_attributes = _urllib_request_moved_attributes
 
-sys.modules[__name__ + ".moves.urllib_request"] = sys.modules[__name__ + ".moves.urllib.request"] = Module_six_moves_urllib_request(__name__ + ".moves.urllib.request")
+_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"""
 
 
@@ -346,10 +444,12 @@ del attr
 
 Module_six_moves_urllib_response._moved_attributes = _urllib_response_moved_attributes
 
-sys.modules[__name__ + ".moves.urllib_response"] = sys.modules[__name__ + ".moves.urllib.response"] = Module_six_moves_urllib_response(__name__ + ".moves.urllib.response")
+_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"""
 
 
@@ -362,22 +462,25 @@ del attr
 
 Module_six_moves_urllib_robotparser._moved_attributes = _urllib_robotparser_moved_attributes
 
-sys.modules[__name__ + ".moves.urllib_robotparser"] = sys.modules[__name__ + ".moves.urllib.robotparser"] = Module_six_moves_urllib_robotparser(__name__ + ".moves.urllib.robotparser")
+_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"""
-    parse = sys.modules[__name__ + ".moves.urllib_parse"]
+    __path__ = []  # mark as package
-    error = sys.modules[__name__ + ".moves.urllib_error"]
+    parse = _importer._get_module("moves.urllib_parse")
-    request = sys.modules[__name__ + ".moves.urllib_request"]
+    error = _importer._get_module("moves.urllib_error")
-    response = sys.modules[__name__ + ".moves.urllib_response"]
+    request = _importer._get_module("moves.urllib_request")
-    robotparser = sys.modules[__name__ + ".moves.urllib_robotparser"]
+    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"),
-sys.modules[__name__ + ".moves.urllib"] = Module_six_moves_urllib(__name__ + ".moves.urllib")
+                      "moves.urllib")
 
 
 def add_move(move):
@@ -404,11 +507,6 @@ if PY3:
     _func_code = "__code__"
     _func_defaults = "__defaults__"
     _func_globals = "__globals__"
-
-    _iterkeys = "keys"
-    _itervalues = "values"
-    _iteritems = "items"
-    _iterlists = "lists"
 else:
     _meth_func = "im_func"
     _meth_self = "im_self"
@@ -418,11 +516,6 @@ else:
     _func_defaults = "func_defaults"
     _func_globals = "func_globals"
 
-    _iterkeys = "iterkeys"
-    _itervalues = "itervalues"
-    _iteritems = "iteritems"
-    _iterlists = "iterlists"
-
 
 try:
     advance_iterator = next
@@ -445,6 +538,9 @@ if PY3:
 
     create_bound_method = types.MethodType
 
+    def create_unbound_method(func, cls):
+        return func
+
     Iterator = object
 else:
     def get_unbound_function(unbound):
@@ -453,6 +549,9 @@ else:
     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):
@@ -471,66 +570,117 @@ get_function_defaults = operator.attrgetter(_func_defaults)
 get_function_globals = operator.attrgetter(_func_globals)
 
 
+if PY3:
     def iterkeys(d, **kw):
-    """Return an iterator over the keys of a dictionary."""
+        return iter(d.keys(**kw))
-    return iter(getattr(d, _iterkeys)(**kw))
 
     def itervalues(d, **kw):
-    """Return an iterator over the values of a dictionary."""
+        return iter(d.values(**kw))
-    return iter(getattr(d, _itervalues)(**kw))
 
     def iteritems(d, **kw):
-    """Return an iterator over the (key, value) pairs of a dictionary."""
+        return iter(d.items(**kw))
-    return iter(getattr(d, _iteritems)(**kw))
 
     def iterlists(d, **kw):
-    """Return an iterator over the (key, [values]) pairs of a dictionary."""
+        return iter(d.lists(**kw))
-    return iter(getattr(d, _iterlists)(**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
-    if sys.version_info[1] <= 1:
+    import struct
-        def int2byte(i):
+    int2byte = struct.Struct(">B").pack
-            return bytes((i,))
+    del struct
-    else:
-        # This is about 2x faster than the implementation above on 3.2+
-        int2byte = operator.methodcaller("to_bytes", 1, "big")
     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])
-    def iterbytes(buf):
+    iterbytes = functools.partial(itertools.imap, ord)
-        return (ord(byte) for byte in buf)
     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
@@ -548,12 +698,26 @@ else:
             _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):
@@ -561,6 +725,7 @@ if print_ is None:
         fp = kwargs.pop("file", sys.stdout)
         if fp is None:
             return
+
         def write(data):
             if not isinstance(data, basestring):
                 data = str(data)
@@ -608,25 +773,96 @@ if print_ is None:
                 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."""
-    return meta("NewBase", bases, {})
+    # 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()
-        orig_vars.pop('__dict__', None)
-        orig_vars.pop('__weakref__', None)
         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)