code: def default_unnormalize(img):
      """Default unnormalization transform which undo the "transforms.Normalize".
  
          Specially, it cancels out mean subtraction and standard deviation division.
  
      Args:
          img (torch.Tensor): image data to which the transform will be applied
  
      """
      # TODO T39752655: Allow this to be configurable
      img = img.clone()
      for channel, std, mean in zip(
          img, ImagenetConstants.STD, ImagenetConstants.MEAN
      ):
          channel.mul_(std).add_(mean)
      return img
  
imports: import collections
  from typing import Any, Callable, Dict, List, Optional, Tuple, Union
  import torchvision.transforms
  from .None import build_transforms, ClassyTransform, register_transform
label_desc: Use image node_id 2 for calling a global function with example usage: default_unnormalize(img) and returns: img