'Gets content ratings on this app keyed by bodies.
es -- denotes whether to return ES-friendly results (just the IDs of
rating classes) to fetch and translate later.'

def get_content_ratings_by_body(self, es=False):

    content_ratings = {}
    for cr in self.content_ratings.all():
        body = cr.get_body()
        rating_serialized = {'body': body.id, 'rating': cr.get_rating().id}
        if (not es):
            rating_serialized = dehydrate_content_rating(rating_serialized)
        content_ratings[body.label] = rating_serialized
    return content_ratings
