code: def _get_mnist(directory):
      """Download all MNIST files to directory unless they are there."""
      for filename in [
          _MNIST_TRAIN_DATA_FILENAME,
          _MNIST_TRAIN_LABELS_FILENAME,
          _MNIST_TEST_DATA_FILENAME,
          _MNIST_TEST_LABELS_FILENAME,
      ]:
          generator_utils.maybe_download(
              directory, filename, _MNIST_URL + filename
          )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import gzip
  import os
  import random
  import numpy
  from tensor2tensor.data_generators import generator_utils
  from tensor2tensor.data_generators import image_utils
  from tensor2tensor.utils import registry
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling a global function with example usage: _get_mnist(directory) without return types