#![allow(unused_variables)]
fn main() {
    use std::rc::Rc;
    let mut data = Rc::new(5);
    *Rc::make_mut(&mut data) += 1;
    let mut other_data = Rc::clone(&data);
    *Rc::make_mut(&mut data) += 1;
    *Rc::make_mut(&mut data) += 1;
    *Rc::make_mut(&mut other_data) *= 2;
    assert_eq!(* data, 8);
    assert_eq!(* other_data, 12);
}