"""Retrieves a list of triggerer_ids."""
        return [row[0] for row in session.query(cls.id).filter(cls.triggerer_id == triggerer_id)]
    @classmethod
    @provide_session
    def assign_unassigned(cls, triggerer_id, capacity, session=None):
        """
        Takes a triggerer_id and the capacity for that triggerer and assigns unassigned
        triggers until that capacity is reached, or there are no more unassigned triggers.