def on_service_departure(self, svc_ref):
        """
        Called when a service has been unregistered from the framework

        :param svc_ref: A service reference
        :return: A tuple (service, reference) if the service has been lost,
                 else None
        """
        with self._lock:
            if svc_ref in self.services:
                # Get the service instance
                service = self.services.pop(svc_ref)

                # Get the key property
                prop_value = svc_ref.get_property(self._key)

                # Remove the injected service
                self.__remove_service(prop_value, service)

                self._ipopo_instance.unbind(self, service, svc_ref)
                return True

            return None
Called when a service has been unregistered from the framework

        :param svc_ref: A service reference
        :return: A tuple (service, reference) if the service has been lost,
                 else None