code: def forward(self, x, edge_index, batch):
      x = self.gnn(x, edge_index)
      x = global_add_pool(x, batch)
      x = self.classifier(x)
      return x
  
file_path: pytorch_geometric/examples/pytorch_lightning/gin.py
imports: import os.path
  import pytorch_lightning
  import torch
  import torch.nn.functional
  from torchmetrics import Accuracy
  import torch_geometric.transforms
  from torch_geometric.data.lightning import LightningDataset
  from torch_geometric.datasets import TUDataset
  from torch_geometric.nn import GIN, MLP, global_add_pool
label_desc: Use image node_id 2 for calling the Model obj's underlying member method code with example usage: obj.forward(x, edge_index, batch) and returns: x