code: def backward(self, x, gy):
      return tuple(g * self.scale for g in gy)
  
file_path: chainerrl/chainerrl/functions/scale_grad.py
imports: import numpy
  import chainer
  from chainer.utils import type_check
label_desc: Use image node_id 4 for calling the ScaleGrad obj's underlying member method code with example usage: obj.backward(x, gy) and returns: tuple