def _add_common_constrain(token_lst: List[Dict], d: Dict) -> List[Dict]:
        """
        Add common constrain for every token type, like "is_required"
        Args:
            token_lst: List[Dict]
            d: Dict

        Returns: List[Dict]
        """

        result = []
        for a_token in token_lst:
            if not tf_transfer(d["is_required"]):
                a_token["OP"] = "?"
            result.append(a_token)
        return result
Add common constrain for every token type, like "is_required"
        Args:
            token_lst: List[Dict]
            d: Dict

        Returns: List[Dict]