code: def test_bf16_hook(
      self,
      has_wrapping: bool,
      sharding_strategy: Optional[ShardingStrategy],
  ):
      state = default_hooks.LowPrecisionState(
          process_group=_get_default_group()
      )
      hook = default_hooks.bf16_compress_hook
  
      self._check_low_precision_hook(
          state, hook, sharding_strategy, torch.bfloat16, has_wrapping
      )
  
imports: import sys
  from typing import Optional
  import torch
  import torch.nn
  import torch.nn.functional
  from torch import distributed
  from torch.distributed.algorithms._comm_hooks import default_hooks
  from torch.distributed.distributed_c10d import _get_default_group
  from torch.distributed.fsdp import FullyShardedDataParallel, MixedPrecision
  from torch.distributed.fsdp.fully_sharded_data_parallel import ShardingStrategy
  from torch.distributed.fsdp.wrap import ModuleWrapPolicy
  from torch.testing._internal.common_distributed import requires_nccl, requires_nccl_version, skip_but_pass_in_sandcastle_if, skip_if_lt_x_gpu
  from torch.testing._internal.common_fsdp import FSDPTest
  from torch.testing._internal.common_utils import instantiate_parametrized_tests, parametrize, run_tests
label_desc: Use image node_id 10 for calling the TestCommunicationHooks obj's underlying member method code with example usage: obj.test_bf16_hook(has_wrapping, sharding_strategy) without return types