code: function delayWhen(delayDurationSelector, subscriptionDelay) {
      if (subscriptionDelay) {
          return function (source) {
              return new SubscriptionDelayObservable(source, subscriptionDelay)
                  .lift(new DelayWhenOperator(delayDurationSelector));
          };
      }
      return function (source) { return source.lift(new DelayWhenOperator(delayDurationSelector)); };
  }
docs: PURE_IMPORTS_START tslib,_Subscriber,_Observable,_OuterSubscriber,_util_subscribeToResult PURE_IMPORTS_END