class_docstr: Simple Stage that stack GNN layers
code: def forward(self, batch):
      for layer in self.children():
          batch = layer(batch)
      if cfg.gnn.l2norm:
          batch.node_feature = F.normalize(
              batch.node_feature, p=2, dim=-1
          )
      return batch
  
file_path: GraphGym/graphgym/contrib/stage/example.py
imports: import torch.nn
  import torch.nn.functional
  from torch_geometric.nn import GCNConv
  from graphgym.config import cfg
  from graphgym.register import register_stage
label_desc: Use image node_id 2 for calling the GNNStackStage obj's underlying member method code with example usage: obj.forward(batch) and returns: batch