code: def test_voxel_grid():
      pos = torch.tensor(
          [
              [0.0, 0.0],
              [11.0, 9.0],
              [2.0, 8.0],
              [2.0, 2.0],
              [8.0, 3.0],
          ]
      )
      batch = torch.tensor([0, 0, 0, 1, 1])
  
      assert voxel_grid(pos, size=5, batch=batch).tolist() == [
          0,
          5,
          3,
          6,
          7,
      ]
      assert voxel_grid(pos, size=5).tolist() == [0, 5, 3, 0, 1]
  
      cluster = voxel_grid(
          pos, size=5, batch=batch, start=-1, end=[18, 14]
      )
      assert cluster.tolist() == [0, 10, 4, 16, 17]
  
      cluster_no_batch = voxel_grid(pos, size=5, start=-1, end=[18, 14])
      assert cluster_no_batch.tolist() == [0, 10, 4, 0, 1]
  
imports: import torch
  from torch_geometric.data import Batch
  from torch_geometric.nn import avg_pool, voxel_grid
  from torch_geometric.testing import withPackage
label_desc: Use image node_id 1 for calling a global function with example usage: test_voxel_grid() without return types