def connectionLost(self, reason):
        """
        Called when the serial port disconnects.

        Will call C{connectionLost} on the protocol that is handling the
        serial data.
        """
        self.reactor.removeEvent(self._overlappedRead.hEvent)
        self.reactor.removeEvent(self._overlappedWrite.hEvent)
        abstract.FileDescriptor.connectionLost(self, reason)
        self._serial.close()
        self.protocol.connectionLost(reason)

        Called when the serial port disconnects.

        Will call C{connectionLost} on the protocol that is handling the
        serial data.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/_win32serialport.py