code: def _init_vocab_from_list(self, vocab_list):
      
      def token_gen():
        for token in vocab_list:
          if token not in RESERVED_TOKENS:
            yield token
  
      self._init_vocab(token_gen())
docs: Initialize tokens from a list of tokens.
  
      It is ok if reserved tokens appear in the vocab list. They will be
      removed. The set of tokens in vocab_list should be unique.
  
      Args:
        vocab_list: A list of tokens.