anchor.diff:     for n in ns do
        HopacCh.run n |> cleanup
      for n in ns do
  +     HopacJob.run n |> cleanup
  +   for n in ns do
  +     Async.run n |> cleanup
  +   for n in ns do
        HopacPromise.run n |> cleanup
      for n in ns do
  -     Async.run n |> cleanup
  +     AsyncMb.run n |> cleanup
  
positive.code:     
  /////////////////////////////////////////////////////////////////////////
  
  module Async =
    type Stream<'a> = MailboxProcessor<AsyncReplyChannel<'a>>
    let inline take (s: Stream<'a>) = s.PostAndAsyncReply (fun x -> x)
  
  
negative.code:       next
  
    let sieve : Job<Stream<_>> =
      let rec sieve nats =
        let prime = nats.Value
        {Value = prime;
         Next =
          Promise.Now.delay (nats.Next >>= filter (fun x -> x % prime <> 0) |>> sieve)}
      iterate (fun x -> x+1) 2 |>> sieve
  
    let primes n = Job.delay <| fun () ->
      let before = GC.GetTotalMemory true
  