public SLL sort_descending() {
        SLLNode curr = null, prev = null, next = null, tmp = null;
        boolean sortingNotFinished = true;

        while(sortingNotFinished) {
            curr = getFirst();
            if(curr == null) return null;

            prev = null;
            next = getFirst().succ;
            sortingNotFinished = false;

            while(next != null) {
                if(curr.id < next.id) {
                    sortingNotFinished = true;

                    if(prev != null) {
                        tmp = next.succ;
                        prev.succ = next;
                        next.succ = curr;
                        curr.succ = tmp;
                    } else {
                        tmp = next.succ;
                        this.first = next;
                        next.succ = curr;
                        curr.succ = tmp;
                    }
                    prev = next;
                    next = curr.succ;
                } else {
                    prev = curr;
                    curr = next;
                    next = next.succ;
                }
            }
        }

        return this;
    }