code: def decode(self, z, edge_label_index):
      return (z[edge_label_index[0]] * z[edge_label_index[1]]).sum(
          dim=-1
      )
  
file_path: pytorch_geometric/examples/link_pred.py
imports: import os.path
  import torch
  from sklearn.metrics import roc_auc_score
  import torch_geometric.transforms
  from torch_geometric.datasets import Planetoid
  from torch_geometric.nn import GCNConv
  from torch_geometric.utils import negative_sampling
label_desc: Use image node_id 3 for calling the Net obj's underlying member method code with example usage: obj.decode(z, edge_label_index) and returns: unknown