def doRead(self):
        """
        Called when my standard output stream is ready for reading.
        """
        return fdesc.readFromFD(
            self.fd,
            lambda data: self.proto.childDataReceived(1, data))

        Called when my standard output stream is ready for reading.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/process.py