message: Add test cases for zip
diff: @@ -158,11 +158,26 @@ class PyBuiltinsTest(test.TestCase):
  start = constant_op.constant(20, dtype=dtypes.int64)
  dataset = py_builtins.enumerate_(dataset, start)
  iterator = dataset_ops.make_one_shot_iterator(dataset)
  -
  with self.cached_session() as sess:
  self.assertAllEqual(self.evaluate(iterator.get_next()), (20, b'a'))
  self.assertAllEqual(self.evaluate(iterator.get_next()), (21, b'c'))
  + def test_zip(self):
  + self.assertListEqual(
  + list(py_builtins.zip_([3, 2, 1], [1, 2, 3])), [(3, 1), (2, 2), (1, 3)])
  + self.assertListEqual(
  + list(py_builtins.zip_([4, 5, 6], [-1, -2])), [(4, -1), (5, -2)])
  +
  + def test_zip_dataset(self):
  + ds1 = dataset_ops.DatasetV2.from_tensor_slices([-11, -12, 4])
  + ds2 = dataset_ops.DatasetV2.from_tensor_slices([-21, -22, 5])
  + ds3 = py_builtins.zip_(ds1, ds2)
  + iterator = dataset_ops.make_one_shot_iterator(ds3)
  + with self.cached_session() as sess:
  + self.assertAllEqual(self.evaluate(iterator.get_next()), (-11, -21))
  + self.assertAllEqual(self.evaluate(iterator.get_next()), (-12, -22))
  + self.assertAllEqual(self.evaluate(iterator.get_next()), (4, 5))
  +
  def _basic_function_scope(self):
  return function_wrappers.FunctionScope(
  'test_function_name',
  