'For merged time-listings, don\'t show items that are too old
(this can happen when mr_top hasn\'t run in a while)'

def keep_fn(self):

    if ((self.time != 'all') and c.default_sr):
        oldest = timeago(('1    %s' % (str(self.time),)))
        def keep(item):
            if isinstance(c.site, AllSR):
                if (not item.subreddit.discoverable):
                    return False
            return ((item._date > oldest) and item.keep_item(item))
        return keep
    else:
        return ListingController.keep_fn(self)
