    def shutdown(self):
        """Shut down the scheduler

        The shut down is not instantenous and
        will occur after the scheduler finishes
        checking one cycle of tasks."""
        warnings.warn((
            "Session.shutdown is deprecated. "
            "Please use Session.shut_down instead"
        ), DeprecationWarning)
        self.scheduler._flag_shutdown.set()
Shut down the scheduler

The shut down is not instantenous and
will occur after the scheduler finishes
checking one cycle of tasks.
rocketry/session.py