- currentSchedulerTScheduler currentScheduler(TScheduler scheduler) 
- currentSchedulerScheduler currentScheduler() 
- historicalSchedulerHistoricalScheduler!TScheduler historicalScheduler(TScheduler scheduler) 
- observeOnObserveOnObservable!(TObservable, TScheduler) observeOn(TObservable observable, TScheduler scheduler) 
- schedulerObjectMostDerivedScheduler!TScheduler schedulerObject(TScheduler scheduler) 
- subscribeOnSubscribeOnObservable!(TObservable, TScheduler) subscribeOn(TObservable observable, TScheduler scheduler) 
This module defines the concept of Scheduler.