'Return rule associated with short_name or None.'

@classmethod
def get_rule(self, subreddit, short_name):

    try:
        rules = self._cf.get(subreddit._id36)
    except tdb_cassandra.NotFoundException:
        return None
    rule = rules.get(short_name, None)
    if (not rule):
        return None
    rule = json.loads(rule)
    rule['short_name'] = short_name
    return rule
