code: def testSymbolicGradientVariableNoneNotZerosLike(self):
      with ops.Graph().as_default():
          v = variables.Variable(1.0)
  
          @polymorphic_function.function
          def f(x, v):
              v.read_value()
              return x * x
  
          x = constant_op.constant(1.0)
          l = f(x, v)
          _, dv = gradients_impl.gradients(l, [x, v])
          with self.cached_session():
              v.initializer.run()
              self.assertEqual(dv, None)
  
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 19 for calling the FunctionGradientsTest obj's underlying member method code with example usage: obj.testSymbolicGradientVariableNoneNotZerosLike() and returns: unknown