code: def aggregate(self, g, z):
      z_list = []
      g.ndata["z"] = z
      g.update_all(fn.copy_u(u="z", out="m"), fn.sum(msg="m", out="z"))
      z_list.append(g.ndata["z"])
      for i in range(self.radius - 1):
          for j in range(2**i):
              g.update_all(
                  fn.copy_u(u="z", out="m"), fn.sum(msg="m", out="z")
              )
          z_list.append(g.ndata["z"])
      return z_list
  
file_path: dgl/examples/pytorch/line_graph/gnn.py
imports: import copy
  import itertools
  import dgl
  import dgl.function
  import networkx
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
label_desc: Use image node_id 2 for calling the GNNModule obj's underlying member method code with example usage: obj.aggregate(g, z) and returns: z_list