anchor.diff:  
           mergeFn(update, pair);
   
  -        if (desc) {
  +        if (_desc) {
             idx = populatePages + i;
   
             if (idx == size) break;
  
positive.code:     int multiplier = 1,
      bool desc = true,
      List<Pair<T>> list,
    }) : this.multiplier = multiplier, this.desc = desc, this.list = list ?? [] {
      this.mainList = this.list;
    }
  
    FetchType get fetchType => _fetchType;
  
    T get latest => desc ? list.first.orig : list.last.orig;
  
    void cbFetchFailed(dynamic e) {
      errmsg = rpc.getErrMsg(e);
  
negative.code:       case FetchType.OLDER:
          if (p == null || p.isEmpty)
            break;
          if (_desc)
            list.addAll(p.map(createFn));
          else
            list.insertAll(0, p.reversed.map(createFn));
  