def test_maximumGroupDiscount(self):
    self.assertEqual(checkout('STXYZ'), (45 + checkout('XY')))
    self.assertEqual(checkout('SSSX'), (45 + checkout('X')))
def test_maximumGroupDiscount(self):
    self.assertEqual(checkout('STXYZ'), (45 + checkout('XY')))
    self.assertEqual(checkout('SSSX'), (45 + checkout('X')))