#![allow(unused_variables)]
fn main() {
    use std::collections::BinaryHeap;
    let mut heap = BinaryHeap::new();
    assert_eq!(heap.peek(), None);
    heap.push(1);
    heap.push(5);
    heap.push(2);
    assert_eq!(heap.peek(), Some(& 5));
    assert_eq!(heap.len(), 3);
    for x in &heap {
        println!("{x}");
    }
    assert_eq!(heap.pop(), Some(5));
    assert_eq!(heap.pop(), Some(2));
    assert_eq!(heap.pop(), Some(1));
    assert_eq!(heap.pop(), None);
    heap.clear();
    assert!(heap.is_empty())
}