In addition to Trial Schedulers like :ref:`ASHA <tune-scheduler-hyperband>`, where a number of
trials are stopped if they perform subpar, Ray Tune also supports custom stopping mechanisms to stop trials early. For instance, stopping mechanisms can specify to stop trials when they reached a plateau and the metric
doesn't change anymore.
Ray Tune comes with several stopping mechanisms out of the box. For custom stopping behavior, you can
inherit from the :class:`Stopper <ray.tune.Stopper>` class.
