code: def __init__(self, grad_stats: GradMemStats):
      self.grad_hook_list = []
      self._grad_stats = grad_stats
  
imports: from contextlib import contextmanager
  from enum import Enum
  from functools import partial
  from typing import List
  import torch
  from colossalai.legacy.zero.gemini.tensor_utils import alloc_storage, free_storage
  from colossalai.tensor.param_op_hook import ColoParamOpHook
  from colossalai.zero.gemini.memory_tracer import MemStats, SyncCudaMemoryMonitor
label_desc: Use image node_id 1 to create a new GradMemTracerHook object  with example: obj = GradMemTracerHook(grad_stats)