public boolean tryAdvance(Consumer<? super LongEntry<V>> action) {
          if (action == null) throw new NullPointerException();
          Node<V> p;
          if ((p = advance()) == null)
              return false;
          action.accept(new SimpleLongEntry<V>(p.key, p.val));
          return true;
      }
public boolean tryAdvance(Consumer<? super LongEntry<V>> action)