def test_double_expression():
exp = parse_expression("4 2 + 3 -")
assert exp[0] == 4
assert exp[1] == 2
assert isinstance(exp[2], Sum)
assert exp[3] == 3
assert isinstance(exp[4], Subtract)
def test_triple_expression():
exp = parse_expression("3 5 8 * 7 + *")
assert exp[0] == 3
assert exp[1] == 5
assert exp[2] == 8
assert isinstance(exp[3], Multiply)
assert exp[4] == 7
assert isinstance(exp[5], Sum)
assert isinstance(exp[6], Multiply)
def test_simple_max_expression():
assert calculate(parse_expression("5 3 4 2 9 1 MAX")) == 9
def test_triple_expression_with_square_root():
assert calculate(parse_expression("20 9 SQRT 5 * +")) == 35
def test_double_expression_with_square_root():
assert calculate(parse_expression("9 SQRT 5 *")) == 15
def test_simple_square_root():
assert calculate(parse_expression("9 SQRT")) == 3
def test_calculate_triple_expression():
assert calculate(parse_expression("3 5 8 * 7 + *")) == 141
def test_calculate_double_expression():
assert calculate(parse_expression("4 2 + 3 -")) == 3
def test_calculate_simple_expression():
assert calculate(parse_expression("20 5 /")) == 4
def test_simple_expression():
exp = parse_expression("20 5 /")
assert exp[0] == 20
assert exp[1] == 5
assert isinstance(exp[2], Divide)