'Returns a tuple that can be used to sort the courses according
the how "new" they are. The "newness" score is computed using a
heuristic that takes into account the announcement and
(advertised) start dates of the course if available.
The lower the number the "newer" the course.'

@property
def sorting_score(self):

    return course_metadata_utils.sorting_score(self.start, self.advertised_start, self.announcement)
