code: def _fetch(self):
      download_url(
          self.__url, self._raw_directory, name=f"{self.__name}.zip"
      )
      _untar(self._raw_directory, f"{self.__name}.zip")
  
imports: import os
  import os.path
  import shutil
  import pickle
  import numpy
  import torch
  import typing
  from autogl.data import Data, download_url, InMemoryStaticGraphSet
  from autogl.data.graph import GeneralStaticGraphGenerator
  from ._dataset_registry import DatasetUniversalRegistry
  from ._data_source import OnlineDataSource
  from ..None import backend
label_desc: Use image node_id 6 for calling the _GTNDataSource obj's underlying member method code with example usage: obj._fetch() without return types