public Set<byte[]> sUnion(byte[]... keys) {
   try {
     if (isPipelined()) {
       pipeline(pipeline.sunion((Object[]) keys));
       return null;
     }
     return SrpUtils.toSet(client.sunion((Object[]) keys).data());
   } catch (Exception ex) {
     throw convertSrpAccessException(ex);
   }
 }