Medium_RetryWhen_4.1.kt

// Our function Zips error emissions with a range to limit them to 3,
// and emits a 0L with a power of 2 based delay
// if limit of retries is reached error is thrown to ensure it reaches
// our subscribe block
val RETRIES_LIMIT = 3
webservice.getRequestSingle()
  .retryWhen { errors: Flowable<Throwable> ->     
    errors.zipWith(
      Flowable.range(1, RETRIES_LIMIT + 1)
      Bifunction<Throwable, Int, Int> { error: Throwable, retryCount: Int ->
        if (retryCount > RETRIES_LIMIT)) {
          throw error 
        } else {
          retryCount                     
        }
      }
    ).flapMap { retryCount: Int ->
        Flowable.timer(
          Math.pow(2.toDouble(), retryCount.toDouble()).toLong(),
          TimeUnit.SECONDS
        )       
    }         
}
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({ data -> 
     //refreshScreenWithData
  }, { error -> 
     //handle error
})