code: def forward_gpu(self, inputs):
      (gy,) = inputs
      gy = _kern()(self.y, gy, self.r)
      return (gy,)
  
imports: import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import function_node
  from chainer.utils import argument
  from chainer.utils import type_check
label_desc: Use image node_id 3 for calling the _RReLUGrad obj's underlying member method code with example usage: obj.forward_gpu(inputs) and returns: gy