def test_light_brightness_can_not_be_negative(self):
self.assertEqual(solve('turn off 0,0 through 0,0'), 0)
def test_returns_correct_result(self):
self.assertEqual(solve('turn on 0,0 through 0,0'), 1)
self.assertEqual(solve('toggle 0,0 through 999,999'), 2*10**6)
