public Future<Long> sortStore(K key, SortArgs sortArgs, K destination) {
   CommandArgs<K, V> args = new CommandArgs<K, V>(codec).addKey(key);
   sortArgs.build(args, destination);
   return dispatch(SORT, new IntegerOutput<K, V>(codec), args);
 }
 public Future<List<V>> sort(K key, SortArgs sortArgs) {
   CommandArgs<K, V> args = new CommandArgs<K, V>(codec).addKey(key);
   sortArgs.build(args, null);
   return dispatch(SORT, new ValueListOutput<K, V>(codec), args);
 }