class_docstr: Head of GNN, node prediction
class_docstr_tok: ["Head","of","GNN",",","node","prediction"]
code: def forward(self, batch):
      batch = self.layer_post_mp(batch)
      pred, label = self._apply_index(batch)
      return pred, label
  
file_path: GraphGym/graphgym/contrib/network/example.py
imports: import torch
  import torch.nn
  import torch.nn.functional
  import torch_geometric.nn
  from torch_geometric.graphgym.models import MLP
  from graphgym.config import cfg
  from graphgym.register import register_network
label_desc: Use image node_id 3 for calling the GNNNodeHead obj's underlying member method code with example usage: obj.forward(batch) and returns: pred,  label