fn main() {
    let country_city = [
        ("UK", "London"),
        ("US", "New York"),
        ("US", "Birmingham"),
        ("UK", "Birmingham"),
    ];

    let mut city_sorted = country_city.clone();
    city_sorted.sort_by_key(|k| k.1);

    let mut country_sorted = country_city.clone();
    country_sorted.sort_by_key(|k| k.0);

    println!("Original:");
    for x in &country_city {
        println!("{} {}", x.0, x.1);
    }

    println!("\nWhen sorted by city:");
    for x in &city_sorted {
        println!("{} {}", x.0, x.1);
    }

    println!("\nWhen sorted by county:");
    for x in &country_sorted {
        println!("{} {}", x.0, x.1);
    }
}