anchor.diff:  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
  +    .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)
  
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: Create async tasks and configure them to:
  
  * Retry errors
  * Control the number of simultaneous operations
  * Limit the number of operations per second
  
  [source,scala,numbered]
  