return navigableKeySet();
    }

    @Override
    public Collection<V> values() {
      return new StandardValues();
    }

    @Override
    public String toString() {
      return standardToString();
    }

    @Override
    public Set<Entry<K, V>> entrySet() {
      return new StandardEntrySet() {
        @Override
        public Iterator<Entry<K, V>> iterator() {