#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn add_one(x: usize) -> usize {
    x + 1
}
fn main() {
    let ptr: fn(usize) -> usize = add_one;
    assert_eq!(ptr(5), 6);
    let clos: fn(usize) -> usize = |x| x + 5;
    assert_eq!(clos(5), 10);
}