def METHOD_NAME(self, path):
    from nnabla.utils.data_source_loader import get_file_extension
    ext = get_file_extension(path)
    if ext not in self.next:
        raise ValueError("Currently, No backend available.")
    else:
        if self.next[ext]:
            self._current_backend = self.next[ext].__class__
            return self.next[ext]
        else:
            raise ValueError("Currently, No backend available.")