Adding an append method to a singly linked list

I was looking through the singly linked list example on rustbyexample.com and I noticed the implementation had no append method, so I decided to try and implement it: fn append(self, elem: u32) -> List { let mut node = &self; loop { match *node { Cons(_, ref tail) => { node = tail; }, Nil => { node.prepend(elem); break; }, } } return self; } The above is one of many different attempts, but I canno