code: def test_influence():
      data = KarateClub()[0]
      x = torch.randn(data.num_nodes, 8)
  
      out = influence(Net(x.size(1), 16), x, data.edge_index)
      assert out.size() == (data.num_nodes, data.num_nodes)
      assert torch.allclose(
          out.sum(dim=-1), torch.ones(data.num_nodes), atol=1e-04
      )
  
file_path: pytorch_geometric/test/visualization/test_influence.py
imports: import torch
  from torch_geometric.datasets import KarateClub
  from torch_geometric.nn import GCNConv
  from torch_geometric.visualization import influence
label_desc: Use image node_id 1 for calling a global function with example usage: test_influence() without return types