def get_policy(self, object_id):
        """
        Return policy of specific object with id
        :param object_id: a filter function, only return objects satisfying this condition
        :return: policy
        """
        if object_id in self._object_policies:
            return self._object_policies[object_id]
        else:
            # print("Can not find the policy for object(id: {})".format(object_id))
            return None

        Return policy of specific object with id
        :param object_id: a filter function, only return objects satisfying this condition
        :return: policy
        
metadrive/engine/base_engine.py