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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def guest_stop(self, userid, **kwargs):
 """Power off a virtual machine. :param str userid: the id of the virtual machine to be power off :param dict kwargs: - timeout=<value>: Integer, time to wait for vm to be deactivate, the recommended value is 300 - poll_interval=<value> Integer, how often to signal guest while waiting for it to be deactivate, the recommended value is 20 :returns: None """


        action = "stop guest '%s'" % userid
        with zvmutils.log_and_reraise_sdkbase_error(action):
            self._vmops.guest_stop(userid, **kwargs)