def killProcess(self):
        """
        Kill the process if it is still running.

        If the process is still running, sends a KILL signal to the transport
        and returns a C{Deferred} which fires when L{processEnded} is called.

        @return: a C{Deferred}.
        """
        if self._processEnded:
            return defer.succeed(None)
        self.onProcessEnd = defer.Deferred()
        self.transport.signalProcess('KILL')
        return self.onProcessEnd

        Kill the process if it is still running.

        If the process is still running, sends a KILL signal to the transport
        and returns a C{Deferred} which fires when L{processEnded} is called.

        @return: a C{Deferred}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_cftp.py