import tensorflow as tf

  filepath = os.path.join(work_directory, filename)
  if not tf.gfile.Exists(filepath):
    temp_file_name, _ = urllib.request.urlretrieve(source_url)
    tf.gfile.Copy(temp_file_name, filepath)
    with tf.gfile.GFile(filepath) as f:
      size = f.size()
