code: def _check_bn(model):
      flag = [False]
      model.apply(lambda module: _check_bn_apply(module, flag))
      return flag[0]
  
imports: from collections import defaultdict
  from torch.optim.optimizer import Optimizer
  import torch
  import warnings
label_desc: Use image node_id 2 for calling a global function with example usage: _check_bn(model) and returns: flag