fn main(){
    let a = &[1, 2, 3];
    for n in a.iter(){
        println!("{}", n);
    }
    for (i, n) in a.iter().enumerate(){
        println!("{}: {}", i, n);
    }
    for (i, n) in a.iter().skip(1).enumerate(){
        println!("{}: {}", i, n);
    }
    let result : Vec<_> = a.iter().zip(a.iter().skip(1)).map(|(a, b)| a*b).collect();
    println!("{:?}", result);
}