#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let a = [1, 2, 3, 4];
    let mut iter = a
        .into_iter()
        .scan(
            1,
            |state, x| {
                *state = *state * x;
                if *state > 6 {
                    return None;
                }
                Some(-*state)
            },
        );
    assert_eq!(iter.next(), Some(- 1));
    assert_eq!(iter.next(), Some(- 2));
    assert_eq!(iter.next(), Some(- 6));
    assert_eq!(iter.next(), None);
}