#![allow(unused_variables)]
fn main() {
    use std::collections::VecDeque;
    let deque: VecDeque<_> = [
        (0, 0),
        (2, 1),
        (4, 1),
        (5, 1),
        (3, 1),
        (1, 2),
        (2, 3),
        (4, 5),
        (5, 8),
        (3, 13),
        (1, 21),
        (2, 34),
        (4, 55),
    ]
        .into();
    assert_eq!(deque.binary_search_by_key(& 13, |& (a, b) | b), Ok(9));
    assert_eq!(deque.binary_search_by_key(& 4, |& (a, b) | b), Err(7));
    assert_eq!(deque.binary_search_by_key(& 100, |& (a, b) | b), Err(13));
    let r = deque.binary_search_by_key(&1, |&(a, b)| b);
    assert!(matches!(r, Ok(1..= 4)));
}