use RefCell;
use Rc;
use Arc;
use Mutex;
// use std::time::Duration;
pub type ArcMut<T> = ;
pub type RcCell<T> = ;
// trait ArcMutex<T> {
// fn arcmut(self) -> ArcMut<T> { arcmut(self) }
// }
// impl<T> ArcMutex<T> for T {
// // fn arcmut(self) -> ArcMut<T> { arcmut(self) }
// }