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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 request_sign_out(self, session=requests):
 """ Send a POST request to the ``ServiceTicket``s logout URL to request sign-out. """

        if logout_allowed(self.service):
            request = SingleSignOutRequest(context={'ticket': self})
            url = get_logout_url(self.service) or self.service
            session.post(url, data={'logoutRequest': request.render_content()})
            logger.info("Single sign-out request sent to %s" % url)