fn main() {
    let a = [1, 2, 3, 4, 5];
    let slice = &a[1..4];
    let mut x: Vec<u8> = vec![Default::default(); 3];
    println!("X at startup: {:?}", x);
    slice.iter().zip(x.iter_mut()).map(|(&s, x)| *x = s).count();
    println!("X copied from vec: {:?}", x);
}