anchor.diff:  
       let actorRef = self.RefPrimary(actor) :> ActorRef
   
  -    actorRef.PostUntyped(TestAsync 42)
  +    actorRef.PostUntyped(TestAsync 42 : TestMessage<int>)
       self.RefPrimary(actor) <!= fun ch -> TestSync(ch, 0)
       cell.Value |> should equal 42
   
  
positive.code:                 |> Actor.start
      let actorRef = self.RefPrimary(actor) :> ActorRef
      
      actorRef.PostWithReplyUntyped((fun ch -> TestSync(ch |> ReplyChannel.map unbox, Default.ReplyReceiveTimeout*4) |> box), Default.ReplyReceiveTimeout/4)
      |> Async.Ignore
      |> Async.RunSynchronously
  
  
negative.code: 
      let actorRef = self.RefPrimary(actor) :> ActorRef
  
      Async.RunSynchronously <| actorRef.AsyncPostUntyped(TestAsync 42 : TestMessage<int>)
      self.RefPrimary(actor) <!= fun ch -> TestSync(ch, 0)
      cell.Value |> should equal 42
  
  