fn encb() {
    let data = {
        let mut data = vec!();
        let d = args().nth(2).unwrap();
        let mut d = File::open(d).unwrap();
        d.read_to_end(&mut data);
        data
    };
    let enc: Vec<u8> = data.iter().map(|v| {
        let v = *v;
        if v == 0 {255}  else {v - 1}
    } ).collect();

    let mut out = File::create("out").unwrap();
    out.write_all(&enc);
}

fn decb() {
    let data = {
        let mut data = vec!();
        let d = args().nth(2).unwrap();
        let mut d = File::open(d).unwrap();
        d.read_to_end(&mut data);
        data
    };
    let dec: Vec<u8> = data.iter().map(|v| {
        let v = *v;
        if v == 255 {0} else {v + 1}
     } ).collect();

    let mut out = File::create("out_d").unwrap();
    out.write_all(&dec).unwrap();
}
