@Override
        public Iterator<Entry<K, V>> iterator() {
          return backingMap.entrySet().iterator();
        }
      };
    }

    @Override
    public void clear() {
      standardClear();
    }

    @Override
    public boolean isEmpty() {
      return standardIsEmpty();
    }

    @Override
    public SortedMap<K, V> subMap(K fromKey, K toKey) {