src/Observable.php
public function timestamp(SchedulerInterface $scheduler = null): Observable
    {
        return $this->lift(function () use ($scheduler) {
            return new TimestampOperator($scheduler ?: Scheduler::getDefault());
        });
    }
public function timestamp(SchedulerInterface $scheduler = null): Observable
    {
        return $this->lift(function () use ($scheduler) {
            return new TimestampOperator($scheduler ?: Scheduler::getDefault());
        });
    }
public function timestamp ( SchedulerInterface $ scheduler = null ) : Observable { return $ this -> lift ( function ( ) use ( $ scheduler ) { return new TimestampOperator ( $ scheduler ? : Scheduler :: getDefault ( ) ) ; } ) ; }
Records the timestamp for each value in an observable sequence.

@param SchedulerInterface|null $scheduler
@return Observable

@demo timestamp/timestamp.php
@operator
@reactivex timestamp
Records the timestamp for each value in an observable sequence .