def writeSomeData(self, data):
        """
        Write some data to the open process.
        """
        rv = fdesc.writeToFD(self.fd, data)
        if rv == len(data) and self.enableReadHack:
            # If the send buffer is now empty and it is necessary to monitor
            # this descriptor for readability to detect close, try detecting
            # readability now.
            self.startReading()
        return rv

        Write some data to the open process.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/process.py