return new SingleIntervalConstrainedNodesEnum(sirenDocsEnum,
levelConstraint, new int[] { lowerBound, upperBound });
}
// if only a level constraint has been set for the current node
else if (levelConstraint != -1) {
return new LevelConstrainedNodesEnum(sirenDocsEnum, levelConstraint);
}
else {
return sirenDocsEnum;
}