pub fn dec_read_dec(i: &mut i32) -> i32 {
*i -= 1;
let ret = *i;
*i -= 1;
ret
}
pub fn minus_1(i: &i32) -> i32 {
dec_read_dec(&mut i.clone())
}
fn main() {
let mut i = 10;
assert_eq!(minus_1(&i), 9);
assert_eq!(i, 10);
assert_eq!(dec_read_dec(&mut i), 9);
assert_eq!(i, 8);
}