code: def gcn_msg(self, edge):
      return {"m": edge.src["x"] * edge.src["norm"]}
  
imports: import dgl.function
  import torch
  import torch.nn.functional
  from torch.nn import Parameter
  from torch_geometric.nn.inits import glorot, zeros
label_desc: Use image node_id 3 for calling the GCNConv obj's underlying member method code with example usage: obj.gcn_msg(edge) and returns: dict