def test_equals_2(self):
     self.assertEqual(solution(1, 2), 3)
 def test_equals_4(self):
     self.assertEqual(solution(1, 1), 1)
 def test_equals(self):
     self.assertEqual(solution(0, 1), 1)
 def test_equals_3(self):
     self.assertEqual(solution(10, 20), 30)