public FileResult ExportExamination(int examinationId, string fileExtension)
        {
            logService.LogManually("Export", "Examination", targetId: examinationId, controller: "ExaminationAPI", method: "ExportExamination", fullname: User.Get(u => u.FullName), usercode: User.Get(u => u.Code));

            ExaminationViewModel exam = examinationService.GetExanById(examinationId);
            string fileName           = exam.Course.Code + "_" + exam.ExamGroup + "_" + exam.ExamCode + "_" + DateTime.Now.ToString("yyyyMMdd");
            List <QuestionInExamViewModel> questions = new List <QuestionInExamViewModel>();

            foreach (var part in exam.PartOfExam)
            {
                questions = questions.Concat(part.Question).ToList();
            }
            if (fileExtension.ToLower().Equals("xml"))
            {
                byte[] byteArray = ExportToXMLFile(questions);
                return(File(byteArray, System.Net.Mime.MediaTypeNames.Application.Octet, fileName + ".xml"));
            }
            else
            {
                byte[] byteArray = ExportToGIFTFile(questions);
                return(File(byteArray, System.Net.Mime.MediaTypeNames.Application.Octet, fileName + ".txt"));
            }
        }