@classmethod
def _get_backend_loader(cls, name):
    """
        Hook called to get the specified backend's loader.
        Should return callable which optionally takes ``"name"`` and/or
        ``"dryrun"`` keywords.

        Callable should return True if backend initialized successfully.

        If backend can't be loaded, callable should return False
        OR raise MissingBackendError directly.
        """
    raise NotImplementedError('implement in subclass')
