code: def world_size(self):
      return 2
  
imports: import os
  import sys
  import tempfile
  import torch
  import torch.distributed
  import torch.multiprocessing
  from torch.testing._internal.common_distributed import MultiProcessTestCase
  from torch.testing._internal.common_utils import load_tests, NO_MULTIPROCESSING_SPAWN
label_desc: Use image node_id 4 for calling the TestDistributedNNFunctions obj's underlying member method code with example usage: obj.world_size() and returns: int