fn print_string(string: String) {
    println!("String: {}", string);
}

fn close_over_string(string: String) -> impl Fn() -> () {
    move || print_string(string)
}

fn main() {
    let string = String::from("hello, world"); // in actual use case, comes from config file.
    let x = close_over_string(string);
    x();
}