def write(self, data):
        """
        We got some data.  Give it back to our C{ProcessProtocol} with
        a newline attached.  Disconnect if there's a null byte.
        """
        self.data += data
        self.proto.outReceived(data)
        self.proto.outReceived(b'\r\n')
        if b'\x00' in data: # mimic 'exit' for the shell test
            self.loseConnection()

        We got some data.  Give it back to our C{ProcessProtocol} with
        a newline attached.  Disconnect if there's a null byte.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_session.py