fn make_multiplier(x: u32) -> impl Fn(u32) -> u32 {
    move |y| y * x
}

fn make_combinator(f: impl Fn(u32) -> u32) -> impl Fn(u32) -> u32 {
    move |x| f(f(f(x)))
}

fn main() {
    println!("{}", make_combinator(make_multiplier(2))(3));
}