code: def initialize_vocabulary(vocabulary_path):
      
      if gfile.Exists(vocabulary_path):
          rev_vocab = []
          with gfile.GFile(vocabulary_path, mode="rb") as f:
              rev_vocab.extend(f.readlines())
          rev_vocab = [tf.compat.as_bytes(line.strip()) for line in rev_vocab]
          vocab = dict([(x, y) for (y, x) in enumerate(rev_vocab)])
          return vocab, rev_vocab
      else:
          raise ValueError("Vocabulary file %s not found.", vocabulary_path)
docs: Initialize vocabulary from file, return the `word_to_id` (dictionary)
      and `id_to_word` (list).
  
      We assume the vocabulary is stored one-item-per-line, so a file will result in a vocabulary {"dog": 0, "cat": 1}, and this function will also return the reversed-vocabulary ["dog", "cat"].
  
      Parameters
      -----------
      vocabulary_path : str
          Path to the file containing the vocabulary.
  
      Returns
      --------
      vocab : dictionary
          a dictionary that maps word to ID.
      rev_vocab : list of int
          a list that maps ID to word.
  
      Examples
      ---------
      >>> Assume 'test' contains
      dog
      cat
      bird
      >>> vocab, rev_vocab = tl.nlp.initialize_vocabulary("test")
      >>> print(vocab)
      >>> {b'cat': 1, b'dog': 0, b'bird': 2}
      >>> print(rev_vocab)
      >>> [b'dog', b'cat', b'bird']
  
      Raises
      -------
      ValueError : if the provided vocabulary_path does not exist.