def test_challenge_4_1(self): equation = '(3 * 4) * 2 + 1' assert challenge4.s(equation) == '3 4 * 2 * 1 +'
def test_challenge_4_2(self): equation = '(5 - 6) * 2 / (1 + 3)' assert challenge4.s(equation) == '5 6 - 2 * 1 3 + /'
def test_challenge_4_8(self): equation = '(((((((((1+2)))))))))' assert challenge4.s(equation) == '1 2 +'
def test_challenge_4_9(self): equation = '(((12)+(21)))' assert challenge4.s(equation) == '12 21 +'
def test_challenge_4_7(self): equation = '((4+7)*12+2)/4' assert challenge4.s(equation) == '4 7 + 12 * 2 + 4 /'
def test_challenge_4_6(self): equation = '4 ^ (3 - 1)' assert challenge4.s(equation) == '4 3 1 - ^'
def test_challenge_4_5(self): equation = '(4 ^ 2) * 3' assert challenge4.s(equation) == '4 2 ^ 3 *'
def test_challenge_4_4(self): equation = '((5 - 3) * ((4 / 2 - 1) * 2))' assert challenge4.s(equation) == '5 3 - 4 2 / 1 - 2 * *'
def test_challenge_4_3(self): equation = '(4 - 1) / (2 - 3)' assert challenge4.s(equation) == '4 1 - 2 3 - /'