code: def forward(self, x, edge_index, edge_weight, batch=None):
      x = self.conv1(x, edge_index, edge_weight).relu()
      x = self.conv2(x, edge_index, edge_weight).relu()
      x = global_add_pool(x, batch)
      x = self.lin(x)
      return x
  
file_path: pytorch_geometric/test/contrib/nn/models/test_rbcd_attack.py
imports: import pytest
  import torch
  from torch.nn import Linear
  from torch_geometric.contrib.nn import GRBCDAttack, PRBCDAttack
  from torch_geometric.nn import GCNConv, global_add_pool
  from torch_geometric.utils import to_undirected
label_desc: Use image node_id 2 for calling the GNN obj's underlying member method code with example usage: obj.forward(x, edge_index, edge_weight, batch) and returns: x