code: def testGraphLoopGradientInsideSession(self):
      with ops.Graph().as_default():
          n = constant_op.constant(2.0)
          x = array_ops.placeholder(dtypes.float32, shape=None)
  
          @polymorphic_function.function
          def f():
              c = lambda n: n < 10
              b = lambda n: n * x
              return while_loop.while_loop(
                  c, b, [n], [tensor_shape.unknown_shape()]
              )
  
          l = f()
          dx = gradients_impl.gradients(l, [x])[0]
  
          with self.cached_session():
              self.assertEqual(dx.eval(feed_dict={x: 2.0}), 24.0)
  
imports: from absl.testing import parameterized
  from tensorflow.python.eager import backprop
  from tensorflow.python.eager import context
  from tensorflow.python.eager.polymorphic_function import polymorphic_function
  from tensorflow.python.framework import config
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import indexed_slices
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import cond
  from tensorflow.python.ops import gradients_impl
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import nn_grad
  from tensorflow.python.ops import nn_ops
  from tensorflow.python.ops import resource_variable_ops
  from tensorflow.python.ops import variable_scope
  from tensorflow.python.ops import variables
  from tensorflow.python.ops import while_loop
  from tensorflow.python.platform import test
label_desc: Use image node_id 16 for calling the FunctionGradientsTest obj's underlying member method code with example usage: obj.testGraphLoopGradientInsideSession() and returns: while_loop