Query#set_sort could return self to allow chaining?

[OJFord]

i.e. instead of:

let query = db.create_query("tag:inbox");
query.set_sort(Sort::NewestFirst);
let result = query.search_messages();

if set_sort returned the Query it could be:

let query = db
    .create_query("tag:inbox")
    .set_sort(Sort::NewestFirst)
    .search_messages();

Also, shouldn't it take &mut self rather than just &self? I realise since it's unsafe/ffi it doesn't need to, but semantically?