code: def save_transformers(
      save_dir: str, transformers: List["dc.trans.Transformer"]
  ):
      """Save the transformers for a MoleculeNet dataset to disk."""
      with open(os.path.join(save_dir, "transformers.pkl"), "wb") as f:
          pickle.dump(transformers, f)
  
imports: import joblib
  import gzip
  import pickle
  import os
  import tempfile
  import tarfile
  import zipfile
  import logging
  from urllib.request import urlretrieve
  from typing import Any, Iterator, List, Optional, Tuple, Union, cast, IO
  import pandas
  import numpy
  import deepchem
label_desc: Use image node_id 19 for calling a global function with example usage: save_transformers(save_dir, transformers) without return types