'Create a line-item description for the donation.
Includes the course display name if provided.
Keyword Arguments:
course_id (CourseKey)
Raises:
CourseDoesNotExistException: The course ID is not valid.
Returns:
unicode'

@classmethod
def _line_item_description(cls, course_id=None):

    if (course_id is not None):
        course = modulestore().get_course(course_id)
        if (course is None):
            msg = u"Could    not    find    a    course    with    the    ID    '{course_id}'".format(course_id=course_id)
            log.error(msg)
            raise CourseDoesNotExistException(_(u"Could    not    find    a    course    with    the    ID    '{course_id}'").format(course_id=course_id))
        return _(u'Donation    for    {course}').format(course=course.display_name)
    else:
        return _(u'Donation    for    {platform_name}').format(platform_name=configuration_helpers.get_value('PLATFORM_NAME', settings.PLATFORM_NAME))
