code: def update(self, aggr_out):
      return aggr_out
  
imports: import torch
  from torch_geometric.nn import MessagePassing
  import torch.nn.functional
  from torch_geometric.nn import global_mean_pool, global_add_pool
  from torch_geometric.utils import degree
  import math
label_desc: Use image node_id 4 for calling the GCNConv obj's underlying member method code with example usage: obj.update(aggr_out) and returns: aggr_out