fn main() {
    let novel = String::from("Call me Ishmael. Some years ago...");
    let first_sentence = novel.split('.')
        .next()
        .expect("Could not find a '.'");
    let i = ImportantExcerpt { part: first_sentence };
    i.announce_and_return_part("hi");
}

struct ImportantExcerpt<'a> {
    part: &'a str,
}

impl<'a> ImportantExcerpt<'a> {
    fn announce_and_return_part<'b, 'c>(&'b self, announcement: &'c str) -> &'a str {
        println!("Attention please: {}", announcement);
        self.part
    }
}