docs: protected boolean updateAssignment(DBIDIter iditer, List<? extends ModifiableDBIDs> clusters, WritableIntegerDataStore assignment, int newA) {
      final int oldA = assignment.intValue(iditer);
      if(oldA == newA) {
        return false;
      }
      clusters.get(newA).add(iditer);
      assignment.putInt(iditer, newA);
      if(oldA >= 0) {
        clusters.get(oldA).remove(iditer);
      }
      return true;
    }