@Override
    public void modulateBy(final Traversal.Admin<?, ?> traversal, final Comparator comparator) {
        this.addComparator((Traversal.Admin<S, C>) traversal, comparator);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/OrderGlobalStep.java