anchor.diff:  Create async tasks and configure them to:
   
   * Retry errors
  -* Control the number of parallel operations
  +* Control the number of simultaneous operations
   * Limit the number of operations per second
   
   [source,scala,numbered]
  
positive.code: https://github.com/S-Mach/s_mach.concurrent[Code]
  http://s-mach.github.io/s_mach.concurrent/#s_mach.concurrent.package[Scaladoc]
  
  == Quick look
  Express parallel Future operations in less lines of code:
  [source,scala,numbered]
  ----
  val read: String => Future[Int] = ???
  
  // Turn this:
  val f1 = read("1")
  val f2 = read("2")
  val f3 = read("3")
  
negative.code: val future : Future[(Int,Double,String)] =
    async // start a new async task
      .par(2) // run 2 ops at a time
      .progress(1.second)(progress => println(progress)) // print progress once a second
      .retry { // retry some errors with a random delay
        case _:TimeoutException =>
          Future.delayed(Random.nextInt(100).millis)(true)
  