'Returns a list of all modes including expired modes for a given course id
Arguments:
course_id (CourseKey): Search for course modes for this course.
Returns:
list of `Mode`'

@staticmethod
def get_course_modes(course_key):

    course_modes = CourseMode.modes_for_course(course_key, include_expired=True)
    return [ModeSerializer(mode).data for mode in course_modes]
