public string Save(EnrollStudentInCourse enrollStudentInCourse)
        {
            EnrollStudentInCourse enrollStudent =
                GetEnrollCourses().ToList().Find(s => (s.StudentId == enrollStudentInCourse.StudentId && s.CourseId == enrollStudentInCourse.CourseId) && (s.Status));

            if (enrollStudent == null)
            {
                if (studentGateway.EnrollStudentInACourse(enrollStudentInCourse) > 0)
                {
                    return("Saved Successfully");
                }
                return("Failed to save");
            }

            return("Already Enroll in this course");
        }