def add_respawn_roads(self, respawn_roads: Union[List[Road], Road]):
        """
        Use this to add spawn roads instead of modifying the list directly
        """
        if isinstance(respawn_roads, List):
            for road in respawn_roads:
                self._add_one_respawn_road(road)
        elif isinstance(respawn_roads, Road):
            self._add_one_respawn_road(respawn_roads)
        else:
            raise ValueError("Only accept List[Road] or Road in this func")

        Use this to add spawn roads instead of modifying the list directly
        
metadrive/component/pgblock/pg_block.py