fn stuff(&mut self) -> impl Future<Output=()> {
    self.coutner = 0;
    future::lazy(|_| {
        self.counter += 1;
        // might be transformed to `self.counter = 1`, since we have a `&mut self`, its safe to assume noone else can edit/access this
    })
}
fn stuff2(&mut self) -> impl Future<Output=()> {
    future::lazy(|_| {
        self.counter += 1;
    })
}