code: def backward(self, indexes, grad_outputs):
      # No trivial way to implement double-backward for this function.
      raise NotImplementedError
  
imports: import numpy
  import six
  from chainer.backends import cuda
  from chainer.backends import intel64
  from chainer import function_node
  from chainer.utils import type_check
label_desc: Use image node_id 5 for calling the LocalResponseNormalizationGrad obj's underlying member method code with example usage: obj.backward(indexes, grad_outputs) without return types