select ListSort(DictKeys(Block(($p)->{
    return FromMutDict(FromDynamicLinear(
        ListFold([1,2,1],ToDynamicLinear(MutDictCreate(Int32,Void,$p)),($item,$state)->{
            return ToDynamicLinear(MutDictInsert(FromDynamicLinear($state),$item,Void()));
        })));
})));