code: def _prepare_reserved_tokens(reserved_tokens):
      """Prepare reserved tokens and a regex for splitting them out of strings."""
      reserved_tokens = [
          tf.compat.as_text(tok) for tok in reserved_tokens or []
      ]
      dups = _find_duplicates(reserved_tokens)
      if dups:
          raise ValueError("Duplicates found in tokens: %s" % dups)
      reserved_tokens_re = _make_reserved_tokens_re(reserved_tokens)
      return reserved_tokens, reserved_tokens_re
  
imports: from __future__ import unicode_literals
  import abc
  import hashlib
  import json
  import re
  from tensorflow_datasets.core.utils.lazy_imports_utils import tensorflow
label_desc: Use image node_id 4 for calling a global function with example usage: _prepare_reserved_tokens(reserved_tokens) and returns: reserved_tokens,  reserved_tokens_re