public final LongEntry<V> next() {
          Node<V> p;
          if ((p = next) == null)
              throw new NoSuchElementException();
          long k = p.key;
          V v = p.val;
          lastReturned = p;
          advance();
        return new SimpleLongEntry<>(k, v);
      }
public final LongEntry<V> next()