class_docstr: Vocabulary extracts set of unique tokens and
  constructs token to index and index to token lookup tables.
class_docstr_tok: ["Vocabulary","extracts","set","of","unique","tokens","and","constructs","token","to","index","and","index","to","token","lookup","tables","."]
code: def to_tokens(self, indices):
      if not isinstance(indices, (list, tuple)):
          return self.idx_to_token[indices]
      return [self.idx_to_token[index] for index in indices]
  
imports: import collections
  import random
  import re
  import jax
  import jax.numpy
  import tensorflow_datasets
  import objax
  from objax.functional import one_hot
  from objax.zoo.rnn import RNN
label_desc: Use image node_id 4 for calling the Vocabulary obj's underlying member method code with example usage: obj.to_tokens(indices) and returns: unknown, self