#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let a = [-1, 2, 3, 4];
    let mut iter = a.into_iter();
    assert_eq!(iter.rposition(| x | x >= 2), Some(3));
    assert_eq!(iter.next(), Some(- 1));
    assert_eq!(iter.next_back(), Some(3));
}