@classmethod
def _get_backend_loader(cls, name):
    """
        subclassed to support legacy 1.6 HasManyBackends api.
        (will be removed in passlib 2.0)
        """
    loader = getattr(cls, '_load_backend_' + name, None)
    if loader is None:

        def loader():
            return cls.__load_legacy_backend(name)
    else:
        assert not hasattr(cls, '_has_backend_' + name
            ), "%s: can't specify both ._load_backend_%s() and ._has_backend_%s" % (
            cls.name, name, name)
    return loader
