code: def test_connection(self) -> None:
      tensor = torch.zeros(10, 10)
      world_size = run_function(debug, tensor, dp=True)
  
      self.assertTrue(
          world_size >= 2,
          f"Need at least 2 gpus but was provided only {world_size}.",
      )
  
imports: import os
  import sys
  import unittest
  import torch
  import torch.distributed
  import torch.multiprocessing
  import torch.nn
  import torch.optim
  from opacus import PrivacyEngine
  from opacus.distributed import DifferentiallyPrivateDistributedDataParallel
  from torch.nn.parallel import DistributedDataParallel
label_desc: Use image node_id 1 for calling the GradientComputationTest obj's underlying member method code with example usage: obj.test_connection() without return types