p.lookup(i * i);

                let v = p.lookup(i * i);
                assert_eq!(v, Some(i * i * i));

    println!("{:?} {:?}", total_put, total_lookup);

    println!("linked-list: {:?} {:?}", total_put, total_lookup);

                p.lookup_ord(i * i);

                let v = p.lookup_ord(i * i);
                assert_eq!(v, Some(i * i * i));

    println!("{:?} {:?}", total_put, total_lookup);

    println!("ordered-vec: {:?} {:?}", total_put, total_lookup);

    println!("{:?} {:?}", total_put, total_lookup);

    println!("skip-list: {:?} {:?}", total_put, total_lookup);