if(isUpdated()) {
System.out.println(this + " isUpdated");
setUpdated(false);
if(hasAllAncestorUpdates()) {
System.out.println(this + " hasAllAncestorUpdates()");
Span span = this.process();
if(span != null) {
List<S> outputs = getOutputSubscriptions();
for(Node<S> nextNode : childNodes) {
nextNode.setModifiedSpan(span, outputs);
}