anchor.diff:          .flatMap { batch =>
             batch.
               .workers
  +            .progress(500.millis)(progress => println(progress))
               .retry {
                 case _: TimeoutException :: tail if tail.size < 3 => true
                 case _: SocketTimeoutException :: _ if tail.size < 3 => true
  
positive.code: +s_mach.concurrent+ allows modifying collection concurrent operations to retry failures and limit iteration speed to a
  specific time period.
  
  .Example 8: Adding retry and throttle control to collection concurrent operations
  [source,scala,numbered]
  ----
  val oomItemIdBatch = (1 to 10).toList.map(_.toString).grouped(2).toList
  
negative.code: working with the scala.concurrent standard library.
  
  * Adds new flow control primitives +concurrently+, +serially+ and +workers+ for control of collection concurrent operations
  * Adds progress reporting, retry and throttle control for collection concurrent operations
  * Adds +ScheduledExecutionContext+, a wrapper for +java.util.concurrent.ScheduledExecutorService+ that provides a functional style interface for scheduling delayed and periodic tasks
  * Adds common concurrent control mechanisms such as concurrent versions of +Latch+, +Lock+, +Semaphore+ and +Queue+
  * Overcomes some design limitations of the scala.concurrent library
  