(feel free to close if you disagree with me that this is a desirable feature)I just had a bug-hunting session that resulted in me accidentally writing code:```rustfn handle_request(request: Request) {    if <"If-None-Match" header with matching ETag was sent> {        Response::empty(304);    }    request.respond(Response::new(..)).unwrap();}```when I meant to write the code:```rustfn handle_request(request: Request) {    if <"If-None-Match" header with matching ETag was sent> {        request.respond(Response::empty(304)).unwrap();        return;    }    request.respond(Response::new(..)).unwrap();}```This attribute will prevent that from happening (though it is backwards-incompatible, so this probably should wait for the next major release).