anchor.diff:  
       module GCHelper =
   
  -        let createListAndMakeSureTheStackframeIsDead () =
  +        let ``create, register callback and return and make sure that the stack frame dies``  () =
               let cset = CSet.ofList [ ]
               let mutable x = cset |> ASet.map ((*)2) |> ASet.filter ((>)(-1000)) |> ASet.groupBy id |> AMap.toASet
           
  
positive.code:             y <- null
              x <- Unchecked.defaultof<_>
              called, cset
              
  
      [<Test>]
      let ``[ASet] registerCallback holds gc root``() =
          let called, inputSet = GCHelper.createListAndMakeSureTheStackframeIsDead ()
  
          let cnt = 1000
          for i in 0 .. cnt do
  
negative.code: 
      [<Test>]
      let ``[ASet] markingCallback holds gc root``() =
          let called, inputSet, reader = GCHelper.``create, register marking and return and make sure that the stack frame dies`` ()
  
          let cnt = 1000
          for i in 0 .. cnt do
              transact (fun () -> CSet.add i inputSet |> ignore)
              //printfn "should equal i=%d called=%d" i !called
              reader.GetDelta() |> ignore
              should equal  i !called
  