internal dynamic EnrollCourse(EnrollCourse aEnrollCourse)
        {
            if (aStudentGateway.EnrolledCourseExist(aEnrollCourse.CourseId))
            {
                return("Course Already Enrolled");
            }

            else if (aStudentGateway.EnrollCourse(aEnrollCourse) > 0)
            {
                return("Enrolled Successfull");
            }
            else
            {
                return("Enrolled failed");
            }
        }