#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let mut v = String::from("hello");
    assert!(v.get_mut(0..5).is_some());
    assert!(v.get_mut(..42).is_none());
    assert_eq!(Some("he"), v.get_mut(0..2).map(| v | &* v));
    assert_eq!("hello", v);
    {
        let s = v.get_mut(0..2);
        let s = s
            .map(|s| {
                s.make_ascii_uppercase();
                &*s
            });
        assert_eq!(Some("HE"), s);
    }
    assert_eq!("HEllo", v);
}