@classmethod
def _get_spec(cls, fullname, path, target=None):
    """Find the loader or namespace_path for this module/package name."""
    # If this ends up being a namespace package, namespace_path is
    #  the list of paths that will become its __path__
    namespace_path = []
    for entry in path:
        if not isinstance(entry, (str, bytes)):
            continue
        finder = cls._path_importer_cache(entry)
    '''
    後略...
    '''