code: def backward(self, state, root_gradients):
      sigmoid_x = state
  
      return root_gradients * sigmoid_x * (1 - sigmoid_x)
  
imports: from __future__ import division, print_function
  import numpy
  import cntk
  from cntk.ops.tests.ops_test_utils import cntk_device, mem_used, os_process
  from cntk.ops.functions import UserFunction
  from cntk import sigmoid
label_desc: Use image node_id 3 for calling the MySigmoid obj's underlying member method code with example usage: obj.backward(state, root_gradients) and returns: unknown