public void visit(OFlow oflow) {
   System.out.println(
       "Adding static OFlow fact: " + oflow.toString() + " (" + oflow.getXPath() + ")");
   visit((OActivity) oflow);
   for (OActivity a : oflow.parallelActivities) {
     a.accept(this);
   }
 }
 public void visit(OSequence osequence) {
   for (OActivity a : osequence.sequence) {
     a.accept(this);
   }
 }