public Seance registerSeance(Seance seance) {
    int index = seances.indexOf(seance);
    if (index == -1) {
      seance.setMovie(registerMovie(seance.getMovie()));
      seance.setRoom(registerRoom(seance.getRoom()));
      addSeance(seance);
      return seance;
    } else {
      Seance foundedSeance = seances.get(index);
      //      Iterator<Ticket> tickets = seance.getTickets();
      //      while (tickets.hasNext()) {
      //        foundedSeance.addTicket(tickets.next());
      //      }
      return foundedSeance;
    }
  }