hex.rs

let hex_string = match hex.len() {
        3 => format!(
            "{}{}{}{}{}{}",
            &hex[..1],
            &hex[..1],
            &hex[1..2],
            &hex[1..2],
            &hex[2..3],
            &hex[2..3]
        ),
        6 => hex.to_string(),
        l => {
            println!("{} has length of {}, expected 3 or 6", hex, l);
            std::process::exit(128)
        }
    };