code: def test(loader):
      model.eval()
  
      total_error = 0
      for data in loader:
          data = data.to(device)
          out = model(
              data.x, data.edge_index, data.edge_attr, data.batch
          )
          total_error += (out.squeeze() - data.y).abs().sum().item()
      return total_error / len(loader.dataset)
  
file_path: pytorch_geometric/examples/pna.py
imports: import os.path
  import torch
  import torch.nn.functional
  from torch.nn import Embedding, Linear, ModuleList, ReLU, Sequential
  from torch.optim.lr_scheduler import ReduceLROnPlateau
  from torch_geometric.datasets import ZINC
  from torch_geometric.loader import DataLoader
  from torch_geometric.nn import BatchNorm, PNAConv, global_add_pool
  from torch_geometric.utils import degree
label_desc: Use image node_id 2 for calling a global function with example usage: test(loader) and returns: unknown