code: def get_instance(cls):
      if cls._instance is None:
          cls._instance = cls.__new__(cls)
          cls._instance.initialize()
      return cls._instance
  
imports: from collections import abc
  from collections import defaultdict
  from copy import deepcopy
  from itertools import chain
  import torch
  import bitsandbytes.functional
label_desc: Use image node_id 3 for calling the GlobalOptimManager obj's underlying member method code with example usage: obj.get_instance(cls) and returns: cls