public void addTicket(Ticket ticket) {
    if (ticket == null) {
      throw new NullObjectInsertionException("null ticket shouldn't be added");
    }

    if (ticket.getSeance() != null && !ticket.getSeance().equals(this)) {
      throw new ReassignObjectException("Ticket already assigned to seance. Ticket could not be reassigned to another seance!");
    }

    if (tickets.contains(ticket)) {
      throw new DuplicateInsertionException("Seance already has same ticket");
    }
    tickets.add(ticket);
    ticket.setSeance(this);
  }