if (metaEdge.isEmpty()) {
AbstractNode source = metaEdge.getSource(viewId);
AbstractNode target = metaEdge.getTarget(viewId);
if(!metaEdge.isSelfLoop() && source.getMetaEdgesInTree().hasNeighbour(target)) {
source.decMutualMetaEdgeDegree();
target.decMutualMetaEdgeDegree();
view.decMutualMetaEdgesTotal(1);
}
source.getMetaEdgesOutTree().remove(metaEdge);
target.getMetaEdgesInTree().remove(metaEdge);
view.decMetaEdgesCount(1);