code: def _split_generators(self, dl_manager):
      
      image_tar_file = os.path.join(dl_manager.manual_dir,
                                    self.builder_config.file_name)
      if not tf.io.gfile.exists(image_tar_file):
        # The current celebahq generation code depends on a concrete version of
        # pillow library and cannot be easily ported into tfds.
        msg = "You must download the dataset files manually and place them in: "
        msg += dl_manager.manual_dir
        msg += " as .tar files. See testing/test_data/fake_examples/celeb_a_hq "
        raise AssertionError(msg)
      return [
          tfds.core.SplitGenerator(
              name=tfds.Split.TRAIN,
              num_shards=50,
              gen_kwargs={"archive": dl_manager.iter_archive(image_tar_file)},
          )
      ]
docs: Returns SplitGenerators.