code: def extra_repr(self):
      return "mean={}, std={}".format(self.mean, self.std)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import torch
  import torch.nn
  import torch.nn.functional
label_desc: Use image node_id 3 for calling the NormalizeByChannelMeanStd obj's underlying member method code with example usage: obj.extra_repr() and returns: str