code: def fetch_column(self, sql, *args, **kwargs):
          
          with self.locked() as conn:
              return conn.query(sql, *args, **kwargs).fetch_column()
docs: Executes an SQL SELECT query and returns the first column of the first row or `None`.
  
          :param sql: statement to execute
          :param args: parameters iterable
          :param kwargs: parameters iterable
          :return: the first row of the first column or `None`