code: def forward(self, x, edge_index):
      x = self.conv1(x, edge_index).relu()
      return self.conv2(x, edge_index)
  
file_path: pytorch_geometric/test/explain/conftest.py
imports: from typing import Optional
  import pytest
  import torch
  from torch_geometric.data import Data, HeteroData
  from torch_geometric.explain import Explanation
  from torch_geometric.explain.config import MaskType
  from torch_geometric.nn import SAGEConv, to_hetero
  from torch_geometric.testing import get_random_edge_index
label_desc: Use image node_id 2 for calling the GraphSAGE obj's underlying member method code with example usage: obj.forward(x, edge_index) and returns: self