src/Observable.php
public static function timer(int $dueTime, AsyncSchedulerInterface $scheduler = null): TimerObservable
    {
        return new TimerObservable($dueTime, $scheduler ?: Scheduler::getAsync());
    }
public static function timer(int $dueTime, AsyncSchedulerInterface $scheduler = null): TimerObservable
    {
        return new TimerObservable($dueTime, $scheduler ?: Scheduler::getAsync());
    }
public static function timer ( int $ dueTime , AsyncSchedulerInterface $ scheduler = null ) : TimerObservable { return new TimerObservable ( $ dueTime , $ scheduler ? : Scheduler :: getAsync ( ) ) ; }
Returns an observable sequence that produces a value after dueTime has elapsed.

@param integer $dueTime - milliseconds
@param AsyncSchedulerInterface $scheduler
@return TimerObservable

@demo timer/timer.php
@operator
@reactivex timer
Returns an observable sequence that produces a value after dueTime has elapsed .