code: def save_vocabulary(self, vocab_path):
          
          index = 0
          if os.path.isdir(vocab_path):
              vocab_file = os.path.join(vocab_path, VOCAB_NAME)
          with open(vocab_file, "w", encoding="utf-8") as writer:
              for token, token_index in sorted(self.vocab.items(), key=lambda kv: kv[1]):
                  if index != token_index:
                      logger.warning("Saving vocabulary to {}: vocabulary indices are not consecutive."
                                     " Please check that the vocabulary is not corrupted!".format(vocab_file))
                      index = token_index
                  writer.write(token + u'\n')
                  index += 1
          return vocab_file
docs: Save the tokenizer vocabulary to a directory or file.