'return the vote status if such record exists, otherwise None'

def getVoteOnChannel(self, channel_id, voter_id):

    if voter_id:
        sql = 'select    vote    from    ChannelVotes    where    channel_id    =    ?    and    voter_id    =    ?'
        return self._db.fetchone(sql, (channel_id, voter_id))
    sql = 'select    vote    from    ChannelVotes    where    channel_id    =    ?    and    voter_id    ISNULL'
    return self._db.fetchone(sql, (channel_id,))
