	private void buildTypeClassMap() throws IOException{
		Reflections reflections = new Reflections("/graphs/\\w+\\.class");
		for ( Class<?> klass : Reflections.getSubClasses(Trace.class, reflections.listClasses("ditl.graphs"))){
			try {
				Field f = klass.getField("type");
				String type = (String)f.get(null);
				type_class_map.put(type, klass);
			} catch (Exception e) {
				System.err.println(klass+": "+e);
			}
		}
	}

	private void buildTypeClassMap() throws IOException{
		Reflections reflections = new Reflections("/\\w+\\.class");
		for ( Class<?> klass : Reflections.getSubClasses(Trace.class, reflections.listClasses("ditl.graphs"))){
			try {
				Field f = klass.getField("type");
				String type = (String)f.get(null);
				type_class_map.put(type, klass);
			} catch (Exception e) {
				System.err.println(klass+": "+e);
			}
		}
	}
