anchor.diff:      let before = GC.GetTotalMemory true
       run <| job {
         do! Job.forUpTo 0 (nCells-1) <| fun i ->
  -            create i |>> fun cell -> cells.[i] <- cell
  +            cell i |>> fun cell -> cells.[i] <- cell
         do printf "%4d b/c " (max 0L (GC.GetTotalMemory true - before) / int64 nCells)
         return!
           seq {1 .. nJobs}
  
positive.code:     let cells = Array.zeroCreate nCells
      let before = GC.GetTotalMemory true
      for i=0 to nCells-1 do
        cells.[i] <- create i
      printf "%4d b/c " (max 0L (GC.GetTotalMemory true - before) / int64 nCells)
      seq {1 .. nJobs}
      |> Seq.map (fun _ -> async {
  
negative.code: 
    type Cell<'a> = MailboxProcessor<Request<'a>>
  
    let cell (x: 'a) : Cell<'a> = MailboxProcessor.Start <| fun inbox ->
      let rec server x = async {
        let! req = inbox.Receive ()
        match req with
  