docs: protected ArrayDBIDs affectedRkNN(List<? extends Collection<DoubleDBIDPair>> extract, DBIDs remove) {
      HashSetModifiableDBIDs ids = DBIDUtil.newHashSet();
      for(Collection<DoubleDBIDPair> drps : extract) {
        for(DoubleDBIDPair drp : drps) {
          ids.add(drp);
        }
      }
      ids.removeDBIDs(remove);
      // Convert back to array
      return DBIDUtil.newArray(ids);
    }