docstr: This function is for illustrative purpose only.
  It is meant to implement a custom reduce-scatter
  of a flattened tensor to all processes in a group.
  Currently a no-op.
docstr_tok: ["This","function","is","for","illustrative","purpose","only",".","It","is","meant","to","implement","a","custom","reduce-scatter","of","a","flattened","tensor","to","all","processes","in","a","group",".","Currently","a","no-op","."]
code: def custom_reduce_scatter(self, output, input, group=None):
      """
      This function is for illustrative purpose only.
      It is meant to implement a custom reduce-scatter
      of a flattened tensor to all processes in a group.
      Currently a no-op.
      """
      pass
  
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 2 for calling the DummyHook obj's underlying member method code with example usage: obj.custom_reduce_scatter(output, input, group) without return types