#![allow(dead_code, deprecated, unused_variables, unused_mut)]
#![feature(iter_order_by)]
use std::cmp::Ordering;
fn main() {
    let xs = [1.0, 2.0, 3.0, 4.0];
    let ys = [1.0, 4.0, 9.0, 16.0];
    assert_eq!(
        xs.iter().partial_cmp_by(ys, | x, y | x.partial_cmp(& y)), Some(Ordering::Less)
    );
    assert_eq!(
        xs.iter().partial_cmp_by(ys, | x, y | (x * x).partial_cmp(& y)),
        Some(Ordering::Equal)
    );
    assert_eq!(
        xs.iter().partial_cmp_by(ys, | x, y | (2.0 * x).partial_cmp(& y)),
        Some(Ordering::Greater)
    );
}