Only sys admins can approve a service
        :param user: a User
        :param data: data that the user wants to update

def can_approve(self, user, **data):
        """
        Only sys admins can approve a service
        :param user: a User
        :param data: data that the user wants to update
        """
        is_external = data.get('service_type', self.service_type) == 'external'
        raise Return(user.is_admin() or is_external)