def close(self):
        """
        Close all pool connections and shutdown the pool.
        """
        if self.shutdownID:
            self._reactor.removeSystemEventTrigger(self.shutdownID)
            self.shutdownID = None
        if self.startID:
            self._reactor.removeSystemEventTrigger(self.startID)
            self.startID = None
        self.finalClose()

        Close all pool connections and shutdown the pool.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/enterprise/adbapi.py