* Returns the last element.
     *
     * @return the last element
     */
    public E getLast() {
        if (isEmpty()) {
            throw new NoSuchElementException();
        }
        return getLastEntry().element;
    }

    /**
     * Returns the first entry.
     *
     * @return the first entry
     */
    public Entry getFirstEntry() {
        if (isEmpty()) {
            return null;
        }