// ! a low-level net
private Set<Set<ClusterElement>> getHandlePairs(String handleType, LowLevelNet n,
Set<AbstractPetriNetElementModel> firstNodeType, Set<AbstractPetriNetElementModel> secondNodeType,
boolean useVanDerAalstModel) {
ArcConfiguration arcConfig = new ArcConfiguration();
Set<Set<ClusterElement>> result = new HashSet<Set<ClusterElement>>();
Iterator<AbstractPetriNetElementModel> i = firstNodeType.iterator();
long time1 = System.nanoTime();