code: def backward(self, indexes, grad_outputs):
      gx = self.get_retained_outputs()[0]
      gy = grad_outputs[0]
      return (gy / (gx * 2.0),)
  
imports: import numpy
  from chainer import backend
  from chainer.backends import cuda
  from chainer import function_node
  from chainer import utils
  from chainer.utils import type_check
  import chainerx
label_desc: Use image node_id 5 for calling the Sqrt obj's underlying member method code with example usage: obj.backward(indexes, grad_outputs) and returns: unknown