anchor.diff:      beforeOrAfter.forEach((record) {
         version = record["version"];
         if (record["action"] == "add") {
  -        logger.info("ACTION ADD");
           if (afterLeqPivot(record)) {
             collectionLength++;
             diff.add(add(record));
  
positive.code:         }
        }
        else if (record["action"] == "change") {
          logger.info("ACTION CHANGE");
          if (beforeLeqPivot(record) && afterLeqPivot(record)) {
            diff.add(change(record));
          }
  
negative.code:     SelectorBuilder selector = createSelector(_rawSelector, __fields, _excludeFields)
                                 .limit(_limit);
      return collection.find(selector).toList().then((data) {
        var version = data.length == 0 ? 0 : data.map((item) => item['__clean_version']).reduce(max);
        if(stripVersion) _stripCleanVersion(data);
        assert(version != null);
  