def get_ctag(self, calendar):
        stuple = (calendar, )
        sql_s = 'SELECT ctag FROM calendars WHERE calendar = ?;'
        try:
            ctag = self.sql_ex(sql_s, stuple)[0][0]
            return ctag
        except __HOLE__:
            return None
dataset/ETHPy150Open pimutils/khal/khal/khalendar/backend.py/SQLiteDb.get_ctag