class_docstr: Tests state_dict and load_state_dict
code: def test_fsdp_ddp(self) -> None:
      self.run_subtests(
          {"use_composable": [True, False]},
          self._test_fsdp_ddp,
      )
  
imports: import copy
  import sys
  from itertools import chain
  from typing import Callable, Tuple
  import torch
  import torch.distributed
  import torch.nn
  from torch.distributed._composable import fully_shard, replicate
  from torch.distributed._shard.sharded_tensor import ShardedTensor
  from torch.distributed._tensor import DTensor, init_device_mesh
  from torch.distributed.checkpoint.state_dict import _patch_model_state_dict, _patch_optimizer_state_dict, get_model_state_dict, get_state_dict, set_model_state_dict, set_state_dict, StateDictOptions
  from torch.distributed.fsdp import FullyShardedDataParallel
  from torch.distributed.fsdp.wrap import ModuleWrapPolicy
  from torch.distributed.optim import _apply_optimizer_in_backward
  from torch.nn.parallel import DistributedDataParallel
  from torch.testing._internal.common_dist_composable import CompositeParamModel, UnitModule
  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.common_state_dict import VerifyStateDictMixin
  from torch.utils._pytree import tree_all, tree_all_only
label_desc: Use image node_id 8 for calling the TestStateDict obj's underlying member method code with example usage: obj.test_fsdp_ddp() without return types