#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let k = 21;
    let x = Some("foo");
    assert_eq!(x.map_or_else(|| 2 * k, | v | v.len()), 3);
    let x: Option<&str> = None;
    assert_eq!(x.map_or_else(|| 2 * k, | v | v.len()), 42);
}