double_ended.rs

fn main() {
    let mut r = vec![1,2,3];
    let mut it = r.iter();
    println!("{:?}", it.next());
    println!("{:?}", it.next_back());
    println!("{:?}", it.next());
    println!("{:?}", it.next());
}

// OUTPUT:
// Some(1)
// Some(3)
// Some(2)
// None