/* (non-Javadoc)
  * @see chu.engine.Stage#onStep()
  */
 @Override
 public void onStep() {
   for (Entity e : entities) {
     e.onStep();
   }
 }
 /* (non-Javadoc)
  * @see chu.engine.Stage#endStep()
  */
 @Override
 public void endStep() {
   for (Entity e : entities) {
     e.endStep();
   }
 }
 /* (non-Javadoc)
  * @see chu.engine.Stage#beginStep()
  */
 @Override
 public void beginStep(List<Message> messages) {
   for (Entity e : entities) {
     e.beginStep();
   }
 }