import tensorflow as tf

        'For large datasets it is better to prepare datasets manually!',
        dataset_name, data_dir)
    if dataset_name.startswith('t2t_'):
      # Download and run dataset generator for T2T problem.
      data_dir = os.path.join(data_dir, dataset_name)
      tf.io.gfile.makedirs(data_dir)
      tf.io.gfile.makedirs(dl_dir)
      t2t_problems().problem(dataset_name[len('t2t_'):]).generate_data(
          data_dir, dl_dir)
    else:
      # Download and prepare TFDS dataset.
      tfds_builder = tfds.builder(dataset_name)
