public string getByTopic(Question.Topics topic)
 {
     return JsonConvert
     .SerializeObject
     (
       Question.questionSeed().Where(q => q.Topic == topic)
     );
 }
 public string getByDificulty(Question.Dificulties dificulty)
 {
     return JsonConvert
     .SerializeObject
     (
       Question.questionSeed().Where(q => q.Dificulty == dificulty)
     );
 }