SynchronizedSortedMap(SortedMap<K, V> m) 
{
            super(m);
            sm = m;
}

 SynchronizedSortedMap(SortedMap<K, V> m,
    Object mutex) 
{
            super(m, mutex);
            sm = m;
}

 public Comparator<? super K> comparator() 
{
            synchronized (mutex) {return sm.comparator();}
}

 public K firstKey() 
{
            synchronized (mutex) {return sm.firstKey();}
}

 public SortedMap<K, V> headMap(K toKey) 
{
            synchronized (mutex) {
                return new SynchronizedSortedMap<  >(sm.headMap(toKey), mutex);
            }
}

 public K lastKey() 
{
            synchronized (mutex) {return sm.lastKey();}
}

 public SortedMap<K, V> subMap(K fromKey,
    K toKey) 
{
            synchronized (mutex) {
                return new SynchronizedSortedMap<  >(
                    sm.subMap(fromKey, toKey), mutex);
            }
}

 public SortedMap<K, V> tailMap(K fromKey) 
{
            synchronized (mutex) {
               return new SynchronizedSortedMap<  >(sm.tailMap(fromKey),mutex);
            }
}