def _get_available_respawn_lanes(self, map: BaseMap) -> list:
        """
        Used to find some respawn lanes
        :param map: select spawn lanes from this map
        :return: respawn_lanes
        """
        respawn_lanes = []
        respawn_roads = []
        for block in map.blocks:
            roads = block.get_respawn_roads()
            for road in roads:
                if road in respawn_roads:
                    respawn_roads.remove(road)
                else:
                    respawn_roads.append(road)
        for road in respawn_roads:
            respawn_lanes += road.get_lanes(map.road_network)
        return respawn_lanes

        Used to find some respawn lanes
        :param map: select spawn lanes from this map
        :return: respawn_lanes
        
metadrive/manager/traffic_manager.py