code: def backend(self):
      return "cpu:gloo,cuda:nccl"
  
imports: import os
  import sys
  import torch
  import torch.distributed
  import torch.distributed.checkpoint
  import torch.nn
  from torch.distributed._tensor import init_device_mesh
  from torch.distributed.checkpoint.state_dict import get_state_dict, set_state_dict, StateDictOptions
  from torch.distributed.fsdp import FullyShardedDataParallel
  from torch.testing._internal.common_distributed import skip_if_lt_x_gpu
  from torch.testing._internal.common_utils import run_tests, TEST_WITH_DEV_DBG_ASAN
  from torch.testing._internal.distributed._tensor.common_dtensor import DTensorTestBase, with_comms
  from torch.testing._internal.distributed.checkpoint_utils import with_temp_dir
label_desc: Use image node_id 2 for calling the TestFineTuning obj's underlying member method code with example usage: obj.backend() and returns: str