code: def _get_pooling_layers(self, start_node_id, end_node_id):
          
          layer_list = []
          node_list = [start_node_id]
          assert self._depth_first_search(end_node_id, layer_list, node_list)
          ret = []
          for layer_id in layer_list:
              layer = self.layer_list[layer_id]
              if is_layer(layer, "Pooling"):
                  ret.append(layer)
              elif is_layer(layer, "Conv") and layer.stride != 1:
                  ret.append(layer)
          return ret
docs: Given two node IDs, return all the pooling layers between them.