#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let xs = [1, 2, 3];
    let mut iter = xs.iter().peekable();
    assert_eq!(iter.peek(), Some(&& 1));
    assert_eq!(iter.next(), Some(& 1));
    assert_eq!(iter.next(), Some(& 2));
    assert_eq!(iter.peek(), Some(&& 3));
    assert_eq!(iter.peek(), Some(&& 3));
    assert_eq!(iter.next(), Some(& 3));
    assert_eq!(iter.peek(), None);
    assert_eq!(iter.next(), None);
}