def __init__(self,
                 sysPath=None,
                 moduleDict=sys.modules,
                 sysPathHooks=sys.path_hooks,
                 importerCache=sys.path_importer_cache,
                 moduleLoader=namedAny,
                 sysPathFactory=None):
        """
        Create a PythonPath.  You almost certainly want to use
        modules.theSystemPath, or its aliased methods, rather than creating a
        new instance yourself, though.

        All parameters are optional, and if unspecified, will use 'system'
        equivalents that makes this PythonPath like the global L{theSystemPath}
        instance.

        @param sysPath: a sys.path-like list to use for this PythonPath, to
        specify where to load modules from.

        @param moduleDict: a sys.modules-like dictionary to use for keeping
        track of what modules this PythonPath has loaded.

        @param sysPathHooks: sys.path_hooks-like list of PEP-302 path hooks to
        be used for this PythonPath, to determie which importers should be
        used.

        @param importerCache: a sys.path_importer_cache-like list of PEP-302
        importers.  This will be used in conjunction with the given
        sysPathHooks.

        @param moduleLoader: a module loader function which takes a string and
        returns a module.  That is to say, it is like L{namedAny} - *not* like
        L{__import__}.

        @param sysPathFactory: a 0-argument callable which returns the current
        value of a sys.path-like list of strings.  Specify either this, or
        sysPath, not both.  This alternative interface is provided because the
        way the Python import mechanism works, you can re-bind the 'sys.path'
        name and that is what is used for current imports, so it must be a
        factory rather than a value to deal with modification by rebinding
        rather than modification by mutation.  Note: it is not recommended to
        rebind sys.path.  Although this mechanism can deal with that, it is a
        subtle point which some tools that it is easy for tools which interact
        with sys.path to miss.
        """
        if sysPath is not None:
            sysPathFactory = lambda : sysPath
        elif sysPathFactory is None:
            sysPathFactory = _defaultSysPathFactory
        self._sysPathFactory = sysPathFactory
        self._sysPath = sysPath
        self.moduleDict = moduleDict
        self.sysPathHooks = sysPathHooks
        self.importerCache = importerCache
        self.moduleLoader = moduleLoader

        Create a PythonPath.  You almost certainly want to use
        modules.theSystemPath, or its aliased methods, rather than creating a
        new instance yourself, though.

        All parameters are optional, and if unspecified, will use 'system'
        equivalents that makes this PythonPath like the global L{theSystemPath}
        instance.

        @param sysPath: a sys.path-like list to use for this PythonPath, to
        specify where to load modules from.

        @param moduleDict: a sys.modules-like dictionary to use for keeping
        track of what modules this PythonPath has loaded.

        @param sysPathHooks: sys.path_hooks-like list of PEP-302 path hooks to
        be used for this PythonPath, to determie which importers should be
        used.

        @param importerCache: a sys.path_importer_cache-like list of PEP-302
        importers.  This will be used in conjunction with the given
        sysPathHooks.

        @param moduleLoader: a module loader function which takes a string and
        returns a module.  That is to say, it is like L{namedAny} - *not* like
        L{__import__}.

        @param sysPathFactory: a 0-argument callable which returns the current
        value of a sys.path-like list of strings.  Specify either this, or
        sysPath, not both.  This alternative interface is provided because the
        way the Python import mechanism works, you can re-bind the 'sys.path'
        name and that is what is used for current imports, so it must be a
        factory rather than a value to deal with modification by rebinding
        rather than modification by mutation.  Note: it is not recommended to
        rebind sys.path.  Although this mechanism can deal with that, it is a
        subtle point which some tools that it is easy for tools which interact
        with sys.path to miss.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/modules.py