class_docstr: Head of GNN, edge prediction
class_docstr_tok: ["Head","of","GNN",",","edge","prediction"]
code: def _apply_index(self, batch):
      return (
          batch.node_feature[batch.edge_label_index],
          batch.edge_label,
      )
  
imports: import torch
  import torch.nn
  import graphgym.register
  from graphgym.config import cfg
  from graphgym.models.layer import MLP
  from graphgym.models.pooling import pooling_dict
label_desc: Use image node_id 2 for calling the GNNEdgeHead obj's underlying member method code with example usage: obj._apply_index(batch) and returns: batch,  batch