subscription = getFaces()
.throttleTime(1000)
.switchMap(face => {
  return Observable.fromPromise(authenticateUserFace(face))
    .catch(err => {
      console.log('Not found')  // I want this to happen after 3 consecutive attempts
                                // But I don't want to retry
                                // I want a new value from the outer observable
      return Observable.empty()
    })
})
.subscribe((token) => {
  console.log('Found')
  console.log(token)
})