message: Add testNestOutputs to tf.function
diff: @@ -147,6 +147,24 @@ class FunctionTest(test.TestCase, parameterized.TestCase):
  out = a_times_b(pair({'a': t}, {'b': t}))
  self.assertAllEqual(out, math_ops.matmul(t, t).numpy())
  + def testNestedOutputsGraphMode(self):
  + matmul = def_function.function(math_ops.matmul)
  +
  + pair = collections.namedtuple('pair', ['a', 'b'])
  +
  + # TODO(b/120222989) remove autograph=False.
  + @def_function.function(autograph=False)
  + def pairs_mul(pair_a, pair_b):
  + return pair(matmul(pair_a.a, pair_b.a), matmul(pair_a.b, pair_b.b))
  +
  + a = constant_op.constant([[1.0, 2.0], [1.0, 2.0]])
  + b = constant_op.constant([[3.0, 4.0], [3.0, 4.0]])
  +
  + out = pairs_mul(pair(a, b), pair(b, a))
  + expected = pair(math_ops.matmul(a, b).numpy(),
  + math_ops.matmul(b, a).numpy())
  + self.assertAllClose(out, expected)
  +
  def testGraphEagerIsolation(self):
  @function.defun
  