code: def _dir_size(directory):
    
    size = 0
    for elem in tf_v1.gfile.ListDirectory(directory):
      elem_full_path = os.path.join(directory, elem)
      stat = tf_v1.gfile.Stat(elem_full_path)
      size += _dir_size(elem_full_path) if stat.is_directory else stat.length
    return size
docs: Returns total size (in bytes) of the given 'directory'.