def test_addOutOfRangeHigh(self):
        """
        L{SerialNumber} cannot be added with other SerialNumber values larger
        than C{_maxAdd}.
        """
        maxAdd = SerialNumber(1)._maxAdd
        self.assertRaises(
            ArithmeticError,
            lambda: SerialNumber(1) + SerialNumber(maxAdd + 1))

        L{SerialNumber} cannot be added with other SerialNumber values larger
        than C{_maxAdd}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_rfc1982.py