#![allow(dead_code, deprecated, unused_variables, unused_mut)]
#![feature(slice_partition_dedup)]
fn main() {
    let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];
    let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);
    assert_eq!(dedup, [10, 20, 30, 20, 11]);
    assert_eq!(duplicates, [21, 30, 13]);
}