code: def forward(self, inputs):
      self.retain_inputs((0,))
      _, y = inputs
      z = self.inv_std[:, None] * y
      self.retain_outputs((0,))
      return (z,)
  
imports: import numpy
  import chainer
  from chainer import backend
  from chainer.backends import cuda
  from chainer import configuration
  from chainer import function_node
  from chainer.utils import type_check
label_desc: Use image node_id 2 for calling the _MulInvStd obj's underlying member method code with example usage: obj.forward(inputs) and returns: z