Can't the function just return `(a.clone, a.clone())`?
Maybe you mean something like this? `fn extend_vec(to: &mut Vec<i32>, from: &Vec<i32>) { ... }`
This does not compile if you pass the same Vec as to and from, because of the `&mut`
Maybe you mean something like this? `fn extend_vec(to: &mut Vec<i32>, from: &Vec<i32>) { ... }`
This does not compile if you pass the same Vec as to and from, because of the `&mut`