public bool isUniqueVacancyKillerQuestion(string question, string vacancyNumber)
 {
     bool isUnique = false;
     VacancyKillerQuestionDAO dao = new VacancyKillerQuestionDAO();
     try
     {
         return (!dao.isFound(vacancyNumber, question));
     }
     catch (InvalidOperationException ioe)
     {
         isUnique = true;
     }
     return isUnique;
 }