code: def test_data_empty_subgraph():
      data = Data(x=torch.arange(5), y=torch.tensor(0.0))
  
      out = data.subgraph(torch.tensor([1, 2, 3]))
      assert "edge_index" not in out
      assert torch.equal(out.x, torch.arange(1, 4))
      assert torch.equal(out.y, data.y)
      assert out.num_nodes == 3
  
imports: import copy
  import pytest
  import torch
  import torch.multiprocessing
  import torch_geometric
  from torch_geometric.data import Data
  from torch_geometric.data.storage import AttrType
  from torch_geometric.testing import get_random_tensor_frame, withPackage
label_desc: Use image node_id 6 for calling a global function with example usage: test_data_empty_subgraph() without return types