docs: def get_meta_graph_def(saved_model_dir, tag_set):
    """Utility function to read a meta_graph_def from disk.
  
    From `saved_model_cli.py <https://github.com/tensorflow/tensorflow/blob/8e0e8d41a3a8f2d4a6100c2ea1dc9d6c6c4ad382/tensorflow/python/tools/saved_model_cli.py#L186>`_
  
    Args:
      :saved_model_dir: path to saved_model.
      :tag_set: list of string tags identifying the TensorFlow graph within the saved_model.
  
    Returns:
      A TensorFlow meta_graph_def, or raises an Exception otherwise.
    """
    saved_model = reader.read_saved_model(saved_model_dir)
    set_of_tags = set(tag_set.split(','))
    for meta_graph_def in saved_model.meta_graphs:
      if set(meta_graph_def.meta_info_def.tags) == set_of_tags:
        return meta_graph_def
    raise RuntimeError("MetaGraphDef associated with tag-set {0} could not be found in SavedModel".format(tag_set))