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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 pause(self):
 """ Pause the VM instance and return the info needed to restart it. """

        if self.instance_id is None:
            raise ValueError("Trying to stop unstarted node.")
        resp = self._cloud_provider.pause_instance(self.instance_id)
        self.preferred_ip = None
        return resp