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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 stop_external_services(self):
 """ Stop all external services. :return: Nothing """

        for service in self._started_services:
            self.logger.debug("Stopping application %s", service.name)
            try:
                service.stop()
            except PluginException:
                self.logger.exception("Stopping external service %s caused and exception!",
                                      service.name)
        self._started_services = []