@Override
 public IDomain computeImageDomain(List<IDomain> sourceDomain) {
   if (sourceDomain.size() <= 1) {
     return AggregateDomain.MANAGER.createMetaDomain(IDomain.NUMERIC, Operators.SUM);
   } else {
     return AnalyticDomain.MANAGER.createMetaDomain(IDomain.NUMERIC);
   }
 }
 @Override
 public ExtendedType computeExtendedType(ExtendedType[] types) {
   if (types.length <= 1) {
     return new ExtendedType(
         AggregateDomain.MANAGER.createMetaDomain(IDomain.NUMERIC), ExtendedType.INTEGER);
   } else {
     return new ExtendedType(
         AnalyticDomain.MANAGER.createMetaDomain(IDomain.NUMERIC), ExtendedType.INTEGER);
   }
 }