code: def testGrad(self):
      def f(a, b):
          return tf_np.sum(tf_np.sqrt(tf_np.exp(a)) + b)
  
      g = extensions.grad(f)
  
      def compare(a, b):
          with tf.GradientTape() as tape:
              tape.watch(a)
              r = f(a, b)
          expected = tape.gradient(r, a)
          self.assertAllEqual(expected, g(a, b))
  
      shape = [10]
      a = tf_np.random.randn(*shape)
      b = tf_np.random.randn(*shape)
      compare(a, b)
  
imports: import functools
  import itertools
  from absl import flags
  from absl.testing import parameterized
  from jax import lax
  import numpy
  import tensorflow.compat.v2
  from trax.tf_numpy import extensions
  import trax.tf_numpy.numpy
label_desc: Use image node_id 6 for calling the ExtensionsTest obj's underlying member method code with example usage: obj.testGrad() and returns: tf_np