def test_Y2038Problem(self):
        """
        L{SerialNumber} raises ArithmeticError when used to add dates more than
        68 years in the future.
        """
        maxAddTime = calendar.timegm(
            datetime(2038, 1, 19, 3, 14, 7).utctimetuple())

        self.assertEqual(
            maxAddTime,
            SerialNumber(0)._maxAdd,
        )

        self.assertRaises(
            ArithmeticError,
            lambda: SerialNumber(0) + SerialNumber(maxAddTime + 1))

        L{SerialNumber} raises ArithmeticError when used to add dates more than
        68 years in the future.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_rfc1982.py