def execCommand(self, pp, command):
        """
        If the command is 'true', store the command, the process protocol, and
        the transport we connect to the process protocol.  Otherwise, just
        store the command and raise an error.
        """
        self.execCommandLine = command
        if command == b'success':
            self.execProtocol = pp
        elif command[:6] == b'repeat':
            self.execProtocol = pp
            self.execTransport = EchoTransport(pp)
            pp.outReceived(command[7:])
        else:
            raise RuntimeError('not getting a command')

        If the command is 'true', store the command, the process protocol, and
        the transport we connect to the process protocol.  Otherwise, just
        store the command and raise an error.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_session.py