def execute(self, remoteCommand, process, sshArgs='', conchArgs=None):
        """
        As for L{OpenSSHClientTestCase.execute}, except it runs the 'conch'
        command line tool, not 'ssh'.
        """
        if conchArgs is None:
            conchArgs = []

        process.deferred = defer.Deferred()
        port = self.conchServer.getHost().port
        cmd = ('-p {} -l testuser '
               '--known-hosts kh_test '
               '--user-authentications publickey '
               '-a '
               '-i dsa_test '
               '-v '.format(port) + sshArgs +
               ' 127.0.0.1 ' + remoteCommand)
        cmds = _makeArgs(conchArgs + cmd.split())
        env = os.environ.copy()
        env['PYTHONPATH'] = os.pathsep.join(sys.path)
        encodedCmds = []
        encodedEnv = {}
        for cmd in cmds:
            if isinstance(cmd, unicode):
                cmd = cmd.encode("utf-8")
            encodedCmds.append(cmd)
        for var in env:
            val = env[var]
            if isinstance(var, unicode):
                var = var.encode("utf-8")
            if isinstance(val, unicode):
                val = val.encode("utf-8")
            encodedEnv[var] = val
        reactor.spawnProcess(process, sys.executable, encodedCmds, env=encodedEnv)
        return process.deferred

        As for L{OpenSSHClientTestCase.execute}, except it runs the 'conch'
        command line tool, not 'ssh'.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_conch.py