@Override
 public RedisClient zunionstore(
     String destkey,
     List<String> sets,
     AggregateOptions options,
     Handler<AsyncResult<Long>> handler) {
   sendLong(
       ZUNIONSTORE,
       RedisCommandUtils.toPayload(
           destkey, sets.size(), sets, options != null ? options.name() : null),
       handler);
   return this;
 }
 @Override
 public RedisClient zunionstoreWeighed(
     String destkey,
     Map<String, Double> sets,
     AggregateOptions options,
     Handler<AsyncResult<Long>> handler) {
   sendLong(
       ZUNIONSTORE,
       RedisCommandUtils.toPayload(
           destkey,
           sets.size(),
           sets.keySet(),
           "WEIGHTS",
           sets.values(),
           options != null ? options.toJsonArray() : null),
       handler);
   return this;
 }