#![allow(dead_code, deprecated, unused_variables, unused_mut)]
#![feature(lazy_cell_into_inner)]
use std::cell::LazyCell;
fn main() {
    let hello = "Hello, World!".to_string();
    let lazy = LazyCell::new(|| hello.to_uppercase());
    assert_eq!(&* lazy, "HELLO, WORLD!");
    assert_eq!(LazyCell::into_inner(lazy).ok(), Some("HELLO, WORLD!".to_string()));
}