code: def _test_nested_wrapper(self, rank, group, config):
      model = NestedWrappedModule(group, config)
      model = FullyShardedDataParallel(model, group, **config).cuda()
      self._test_grad_acc(model, batch_dim=0)
  
imports: import contextlib
  import functools
  import itertools
  import unittest
  from unittest.mock import patch
  from parameterized import parameterized
  import torch
  from fairscale.fair_dev.testing.testing import DummyProcessGroup, make_cudnn_deterministic, objects_are_equal
  from fairscale.nn.data_parallel import FullyShardedDataParallel
  from .test_fsdp import DistributedTest, NestedWrappedModule, rename_test, spawn_and_init
label_desc: Use image node_id 7 for calling the TestGradAcc obj's underlying member method code with example usage: obj._test_nested_wrapper(rank, group, config) without return types