code: def __call__(self, features: Features) -> Features:
      for k in self.data_keys:
          features[k] = self.sp_tokenizer.tokenize(features[k])
      return features
  
file_path: flax/examples/wmt/tokenizer.py
imports: import dataclasses
  import os
  import tempfile
  import time
  from typing import Any, Dict, Iterable, Tuple
  from absl import logging
  import jax
  import tensorflow
  import tensorflow_text
  from sentencepiece import SentencePieceTrainer
label_desc: Use image node_id 1 for calling the TokenizeOp obj's underlying member method code with example usage: obj.__call__(features) and returns: features