class_docstr: Combines multiple KeyedOptimizers into one.
  
  Meant to combine different optimizers for different submodules
class_docstr_tok: ["Combines","multiple","KeyedOptimizers","into","one",".","Meant","to","combine","different","optimizers","for","different","submodules"]
code: def zero_grad(self, set_to_none: bool = False) -> None:
      for _, opt in self._optims:
          opt.zero_grad(set_to_none=set_to_none)
  
imports: import json
  from copy import deepcopy
  from typing import Any, Callable, Collection, Dict, List, Mapping, Optional, OrderedDict, Set, Tuple, Union
  import torch
  from torch import optim
  from torchrec.distributed.types import ShardedTensor
label_desc: Use image node_id 3 for calling the CombinedOptimizer obj's underlying member method code with example usage: obj.zero_grad(set_to_none) without return types