def unregisterProducer(self):
        """
        Unregister a producer.

        If TLS is enabled, the TLS connection handles this.
        """
        if self.TLS:
            self.protocol.unregisterProducer()
        else:
            abstract.FileHandle.unregisterProducer(self)

        Unregister a producer.

        If TLS is enabled, the TLS connection handles this.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/iocpreactor/tcp.py