struct Cat {
    // data
}

struct Person<'a> {
    cat: &'a Cat, // because cats can be shared
}

impl<'a> Person<'a> {
    fn new(cat: &'a Cat, second_cat: &Cat) -> Person<'a> {
        Person { cat }
    }
}

fn good_lifetime_use() {
    let cat = Cat {};
    // this compiles: the other_cat does not have to be valid for the Person to be valid
    let p = {
        let other_cat = Cat {};

        Person::new(&cat, &other_cat)
    };
}

// this does not compile: the variable `other_cat`` needs to be valid for the Person to ba valid
// but `other _cat` reaches the end of its scope...
fn bad_lifetime_use() {
    let cat = Cat {};
    let p = {
        let other_cat = Cat {};

        Person::new(&other_cat, &cat)
    };
}