checkGraph(schedule);
    public static void doit(LinkedList schedule)     {	HashSet alreadyScheduled = new HashSet();	Iterator traces = schedule.iterator();	while (traces.hasNext()) {	    Trace trace = (Trace)traces.next();	    incrementUpstream(trace, alreadyScheduled);	    alreadyScheduled.add(trace);	}	//check graph 	//everything one more than downstream...no    }