code: def iter_move_grads_and_optimizers(
      gm: IterGraphModule,
      target_comm_node: str,
      target_dest_node: str,
  ) -> None:
      """Extract a comm block and split out a new optimizer and step for it.
  
      This subgraph is then moved to the forward graph.
      """
      for comm_block in get_all_comm_blocks(gm, "all_reduce"):
          if comm_block.comm_node.name == target_comm_node:
              break
      else:
          raise ValueError(f"Cannot find {target_comm_node}")
  
      optim_blocks = get_all_fused_optimizer_blocks(gm, "_fused_adam")
      for optim_block in optim_blocks:
          optim_args = AdamArgs(*optim_block.optim.optim_node.args)
          one_output = next(iter(comm_block.outputs))
          if one_output in optim_args.grads:
              break
      else:
          raise ValueError(
              f"{target_comm_node} is not used by any fused optimizer."
          )
  
      move_optim, _ = split_fused_optimizer(
          gm, optim_block, comm_block.outputs
      )
  
      move_nodes = find_all_descendants(
          gm, [comm_block.comm_node, move_optim.step.add_node]
      )
  
      stop_node = find_node(
          gm.graph, lambda n: n.name == target_dest_node
      )[0]
  
      gm.graph.move_to_next_iter_before(move_nodes, stop_node)
  
imports: import collections
  import itertools
  import logging
  import operator
  import tempfile
  import time
  from dataclasses import dataclass, field
  from functools import wraps
  from typing import Any, Callable, cast, DefaultDict, Dict, Iterable, List, Optional, Set, Tuple, Union
  import torch
  import torch.fx
  from torch._subclasses.fake_tensor import FakeTensor, FakeTensorMode
  from torch.distributed._spmd.graph_utils import CommType, dump_graphs_to_files, find_node, get_output, OP
  from torch.distributed._spmd.iter_graph_module import IterGraphModule
  from torch.fx.passes.shape_prop import TensorMetadata
  from torch.utils import _pytree
  from torch.utils._pytree import tree_flatten, tree_unflatten
label_desc: Use image node_id 18 for calling a global function with example usage: iter_move_grads_and_optimizers(gm, target_comm_node, target_dest_node) without return types