public void addTransition(Transition t) {
		try {
			int ttapes = ((TMTransition) t).tapes();
			if (tapes == 0)
				tapes = ttapes;
			if (ttapes != tapes)
				throw new IllegalArgumentException("Transition has " + ttapes
						+ " tapes while TM has " + tapes);
			super.addTransition(t);
		} catch (ClassCastException e) {

		}
	}