code: def vocab(self):
      # type: () -> List[str]
      if self._vocab is None:
          self._vocab = sorted(set(self.tokens))
      return self._vocab
  
imports: from __future__ import absolute_import
  import re
  import math
  from typing import List, Tuple, Union, Optional
  import numpy
  from sklearn.utils import check_random_state
  from eli5.utils import indices_to_bool_mask, vstack
label_desc: Use image node_id 5 for calling the TokenizedText obj's underlying member method code with example usage: obj.vocab() and returns: self