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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, user):
 """ Send a single logout request to each service accessed by a specified user. This is called at logout when single logout is enabled. If requests-futures is installed, asynchronous requests will be sent. Otherwise, synchronous requests will be sent. """

        session = Session()
        for ticket in self.filter(user=user, consumed__gte=user.last_login):
            ticket.request_sign_out(session=session)