code: def world_size(self) -> int:
      return min(torch.cuda.device_count(), 4)
  
imports: import os
  import sys
  import unittest
  from packaging.version import Version, parse
  import torch
  from torch import distributed
  from torch.utils import collect_env
  from torch.testing._internal import common_utils
  from torch.testing._internal import common_distributed
  from apex.transformer._ucc_util import HAS_UCC
label_desc: Use image node_id 4 for calling the DistributedTestBase obj's underlying member method code with example usage: obj.world_size() and returns: min