//@ is mutable, we can use a mutable iterator, providing mutable references to the elements.
fn vec_inc(v: &mut Vec<i32>) {
for e in v.iter_mut() {
//@ is mutable, we can use a mutable iterator, providing mutable references to the elements.
fn vec_inc(v: &mut Vec<i32>) {
for e in v.iter_mut() {