code: def _subtoken_ids_to_tokens(self, subtokens):
      
      escaped_tokens = "".join([
          self.subtoken_list[s] for s in subtokens
          if s < len(self.subtoken_list)])
      escaped_tokens = escaped_tokens.split("_")
  
      # All tokens in the vocabulary list have been escaped (see _escape_token())
      # so each token must be unescaped when decoding.
      ret = []
      for token in escaped_tokens:
        if token:
          ret.append(_unescape_token(token))
      return ret
docs: Convert list of int subtoken ids to a list of string tokens.