#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::cell::OnceCell;
fn main() {
    let mut cell: OnceCell<String> = OnceCell::new();
    assert_eq!(cell.take(), None);
    let mut cell = OnceCell::new();
    let _ = cell.set("hello".to_owned());
    assert_eq!(cell.take(), Some("hello".to_owned()));
    assert_eq!(cell.get(), None);
}