def test_invalid_string_multiply(string, out_string): assert calc(string) == out_string, f"error with processing {string}"
def test_invalid_string_divide(string, out_string): assert calc(string) == out_string, f"error with processing {string}"
def test_valid_string_minus(string, out_string): assert calc(string) == out_string, f"error with processing {string}"