fn main() {
    let s = "ich grüße die welt!";
    let start = s.char_indices().skip(4).next().unwrap().0;
    let end = s.char_indices().skip(4 + 5).next().unwrap().0;
    match &s[start..end] {
        "grüße" => dbg!("hmmm"),
        s => dbg!(s),
    };
}