def registerProducer(self, producer, streaming):
        """
        Call this to register producer for standard input.

        If there is no standard input producer.stopProducing() will
        be called immediately.
        """
        if 0 in self.pipes:
            self.pipes[0].registerProducer(producer, streaming)
        else:
            producer.stopProducing()

        Call this to register producer for standard input.

        If there is no standard input producer.stopProducing() will
        be called immediately.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/process.py