anchor.diff:  
   
       member this.HandleSwipe(gr : UISwipeGestureRecognizer) =
  -        printfn "%A" gr.Direction
  +        this.MySnakeView.MoveTowards <| 
  +        match gr.Direction with
  +        | UISwipeGestureRecognizerDirection.Up -> Up
  +        | UISwipeGestureRecognizerDirection.Left -> Left
  +        | UISwipeGestureRecognizerDirection.Right -> Right
  +        | UISwipeGestureRecognizerDirection.Down -> Down
  +        | _ -> Up
   
       // Return true for supported orientations
       override this.ShouldAutorotateToInterfaceOrientation(orientation) = 
  
positive.code:             this.View.Bounds.Height - 50.0f,
              100.0f,
              44.0f)
          b.TouchUpInside.Add (fun x -> sv.Step())
          this.View.AddSubview(b)
  
          let lft = new UISwipeGestureRecognizer(Action<_> this.HandleSwipe)
  
negative.code:         let im = new UIImage("ziggy.jpg")
          iv.Image <- im
          this.View.AddSubview(iv)
          this.MySnakeView.Frame <- RectangleF(
              this.View.Bounds.X + 10.0f,
              this.View.Bounds.Y + 10.0f,
              this.View.Bounds.Width - 20.0f,
              this.View.Bounds.Height - 20.0f)
          this.View.AddSubview(this.MySnakeView)
          let b = UIButton.FromType(UIButtonType.System)
          b.SetTitle("Update", UIControlState.Normal)
          b.Frame <- RectangleF(
  