public List<Course> requestAllCourses() {
   List<Course> coursesList = new ArrayList<Course>();
   for (Course course : courseRepository.findAll()) {
     coursesList.add(course);
   }
   return coursesList;
 }
 public Course getCourseBySequence(Integer courseSequence) {
   Course course = courseRepository.findBySequence(courseSequence);
   return course;
 }