You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: scytale.rs
    path of file: ./repos/CaptfEncoder/CaptfEncoder-V3/encoding/src/classical/internal/cipher_crypt
    
    the code of the file until where you have to start completion: //! One of the oldest cryptography tools was a scytale,
    
    fn longer_msg() {
        let s = Scytale::new(7);
        let m = concat!(
            "We attack at dawn, not later when it is light, ",
            "or at some strange time of the clock. Only at dawn. ",
            "Why do we like to attack at dawn, actually, I don\'t ",
            "get it. I hate getting up that early, it puts me in ",
            "a bad mood. Can\'t we do it a bit later, say nine-thirty?"
        );
        assert_eq!(m, s.decrypt(&s.encrypt(m).unwrap()).unwrap());
    }