def _bufferedWrite(self, octets):
        """
        Put the given octets into L{TLSMemoryBIOProtocol._appSendBuffer}, and
        tell any listening producer that it should pause because we are now
        buffering.
        """
        self._appSendBuffer.append(octets)
        if self._producer is not None:
            self._producer.pauseProducing()

        Put the given octets into L{TLSMemoryBIOProtocol._appSendBuffer}, and
        tell any listening producer that it should pause because we are now
        buffering.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/tls.py