Used in https://github.com/mhenc/airflow/blob/master/airflow/dag_processing/manager.py#L613

should be straighforward
warnings.warn(
            "`DAG.normalize_schedule()` is deprecated.",
            category=RemovedInAirflow3Warning,
            stacklevel=2,
        )
        with warnings.catch_warnings():
            warnings.simplefilter("ignore", RemovedInAirflow3Warning)
            following = self.following_schedule(dttm)
        if not following:  
            return dttm
        with warnings.catch_warnings():
            warnings.simplefilter("ignore", RemovedInAirflow3Warning)
            previous_of_following = self.previous_schedule(following)
        if previous_of_following != dttm:
            return following
        return dttm
    @provide_session
    def get_last_dagrun(self, session=NEW_SESSION, include_externally_triggered=False):