def get_respawn_lanes(self):
        """
        return a 2-dim array [[]] to keep the lane index
        """
        ret = []
        for road in self._respawn_roads:
            lanes = road.get_lanes(self.block_network)
            ret.append(lanes)
        return ret

        return a 2-dim array [[]] to keep the lane index
        
metadrive/component/block/base_block.py