class_docstr: 用于Dummy pytorch的GradScaler对象，防止重复写大量的if判断
code: def unscale_(self, optimizer):
      pass
  
imports: import os
  from typing import Any, Dict, Optional, Union
  from enum import IntEnum
  import contextlib
  import random
  import numpy
  import inspect
  from fastNLP.envs.imports import _NEED_IMPORT_TORCH
  from fastNLP.envs.utils import get_global_seed
  from fastNLP.envs import get_global_rank, FASTNLP_BACKEND_LAUNCH, FASTNLP_GLOBAL_SEED
  from fastNLP.core.samplers import re_instantiate_sampler, ReproducibleBatchSampler, ReproducibleSampler
  from fastNLP.core.utils import auto_param_call, apply_to_collection
  from fastNLP.core.log import logger
label_desc: Use image node_id 7 for calling the DummyGradScaler obj's underlying member method code with example usage: obj.unscale_(optimizer) without return types