private static <T> Letter<?> createRandomLetter(Inhabitant senderI,
			Inhabitant receiverI) {
		Random rand = new Random();
		Letter<?> letter;
		Random rand2 = new Random();
		switch (rand.nextInt(5)) {
		case 0:
			letter = new PromissoryNote(senderI, receiverI, new Money(
					rand2.nextInt(100)));
			break;
		case 1:
			letter = new RegistredLetter<Letter<?>>(createRandomLetter(senderI,
					receiverI));
			break;
		case 2:
			letter = new UrgentLetter<Letter<?>>(createRandomLetter(senderI,
					receiverI));
			break;
		default:
			letter = new SimpleLetter(senderI, receiverI, new Text(
					"bonjour " + receiverI.toString()));
		}
		return letter;
	}