code: def dgmg_reduce(self, nodes, round):
      hv_old = nodes.data["hv"]
      m = nodes.mailbox["m"]
      message = torch.cat(
          [hv_old.unsqueeze(1).expand(-1, m.size(1), -1), m], dim=2
      )
      node_activation = (self.message_funcs[round](message)).sum(1)
  
      return {"a": node_activation}
  
imports: import os
  import dgl
  import torch.nn
  import torch
  from functools import partial
  import torch.nn.functional
  from torch.distributions import Bernoulli
  from torch.distributions import Categorical
  import torch.utils.model_zoo
label_desc: Use image node_id 3 for calling the GraphProp obj's underlying member method code with example usage: obj.dgmg_reduce(nodes, round) and returns: dict