Rust question

gistfile1.txt

   Compiling bubblerust v0.1.0 (/home/stephanie/Projects/Rust/bubblerust)
error[E0308]: mismatched types
  --> src/main.rs:17:33
   |
17 |     println!("{:?}", bubblesort(&list));
   |                                 ^^^^^ types differ in mutability
   |
   = note: expected mutable reference `&mut Vec<u32>`
                      found reference `&Vec<u32>`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.
error: could not compile `bubblerust`.

To learn more, run the command again with --verbose.

main.rs

fn bubblesort(l: &mut Vec<u32>) -> &mut Vec<u32> {
    (*l).push(100);
    l
}


fn main() {
    let mut list: Vec<u32> = Vec::new();
    list.push(20);
    list.push(40);
    list.push(10);
    list.push(50);
    list.push(5);
    list.push(1);

    println!("{:?}", bubblesort(&list));
}