Function executor

effect/src/createEffect.ts:179–187

(req: Request)

      switchMap((status) => (status ? of(status) : Promise.resolve(status))),
      distinctUntilChanged()
    )
    .subscribe(isActive);
  mainSub.add(activitySub);

  // Allows global shutdown
  const shutdownSub = allShutdowns.subscribe(() => {
    shutdownSelf();
  });

  function shutdownSelf() {
    currentCancel.next(); // terminate us
    batch.next(); // terminate current batch