Rust sort Vec of &str or String, in place, case insensitive

insensitive_sort.rs

fn insensitive_sort<T: AsRef<str>>(users: &mut Vec<T>) {
    users.sort_by_cached_key(|a: &T| a.as_ref().to_lowercase());
}

fn main() {
    let mut users: Vec<String> = vec![String::from("zzz"), String::from("xxx")];
    insensitive_sort(&mut users);
    println!("{:?}", users);

    let mut users: Vec<&str> = vec!["Todd", "amy"];
    insensitive_sort(&mut users);
    println!("{:?}", users);
}