class_docstr: This PG only supports world_size of 1
class_docstr_tok: ["This","PG","only","supports","world_size","of","1"]
code: def size(self):
      return self._world
  
imports: import os
  import torch
  import torch.distributed
  from torch.testing._internal.common_utils import run_tests
  from torch.futures import Future
  import torch.nn
  from torch.nn.parallel import DistributedDataParallel
  import test_c10d_common
  import weakref
  from torch._C._distributed_c10d import _create_work_from_future
  from torch.testing._internal.common_distributed import MultiProcessTestCase
label_desc: Use image node_id 5 for calling the LonelyRankProcessGroup obj's underlying member method code with example usage: obj.size() and returns: self