How to use the esp-js.ObservationStage.committed function in esp-js

    private _observeEvent = (eventType: string | string[], stage: ObservationStage = ObservationStage.committed): Rx.Observable> => {
        return Rx.Observable.create((obs: Rx.Observer) => {
                const events = typeof eventType === 'string' ? [eventType] : eventType;
                const espEventStreamSubscription = this._router
                    .getAllEventsObservable(events, stage)
                    .filter(eventEnvelope => eventEnvelope.modelId === this._modelId)
                    .subscribe(
                        (eventEnvelope: EventEnvelope>) => {
                            logger.verbose(`Passing event [${eventEnvelope.eventType}] at stage [${eventEnvelope.observationStage}] for model [${eventEnvelope.modelId}] to eventStream.`);
                            let inputEvent: InputEvent = this._mapEventEnvelopToInputEvent(eventEnvelope);
                            // Pass the event off to our polimer observable stream.
                            // In theory, these streams must never error.
                            // They need to bake in their own exception handling.
                            // We wrap in a try catch just to stop any exception bubbling to the router
                            try {
                                obs.onNext(inputEvent);
                            } catch (err) {

    (eventName: string | string[], stage: string = ObservationStage.committed): Rx.Observable> => {
        return Rx.Observable.create(obs => {
            const events = typeof eventName === 'string'
                ? new Set(eventName)
                : new Set(eventName);

            const stream = router.getAllEventsObservable()
                .filter(envelope => envelope.observationStage === stage)
                .filter(envelope => events.has(envelope.eventType))
                .map>(payload => ({
                    ...payload,
                    store
                }));

            return stream.subscribe(
                payload => {
                    logger.debug('Received esp-js payload. Passing the payload onto the polimer observables.', payload);

export function eventTransformFor(eventType: string, observationStage = ObservationStage.committed) {
    return function (target, name, descriptor) {
        Guard.stringIsNotEmpty(eventType, 'eventType passed to an observeStoreEvent decorator must not be \'\'');
        let metadata: EspMetadata  = EspDecoratorUtil.getOrCreateMetaData(target.constructor);
        metadata.addEvent(
            name,
            eventType,
            DecoratorTypes.custom,
            observationStage,
            null
        );
        return descriptor;
    };
}