Err(_)
        ))
    }
    #[test]
    fn no_lone_star() {
        assert!(matches!(
            parse(b"*"),
            Err(_)
        ))
    }
    #[test]
    fn no_lone_plus() {
        assert!(matches!(
            parse(b"+"),
            Err(_)
        ))
    }
    #[test]
    fn no_lone_question() {
        assert!(matches!(
            parse(b"?"),