def activate(self, user):
        """
        Updates the `invitee` value and saves the instance

        Provided as a way of extending the behavior.

        Args:
            user: the newly created user

        Returns:
            the linking organization user

        """
        org_user = self.organization.add_user(user, **self.activation_kwargs())
        self.invitee = user
        self.save()
        return org_user