anchor.diff:  
           override this.Equals that =
               match that with
  -            | :? Layer as that -> this.LayerAddress == that.LayerAddress
  +            | :? Layer as that -> this.LayerAddress.Equals that.LayerAddress
               | _ -> failwithumf ()
   
           override this.GetHashCode () = this.LayerAddress.GetHashCode ()
  
positive.code: 
          override this.Equals that =
              match that with
              | :? Screen as that -> this.ScreenAddress == that.ScreenAddress
              | _ -> failwithumf ()
  
          override this.GetHashCode () = this.ScreenAddress.GetHashCode ()
  
negative.code: 
          override this.Equals that =
              match that with
              | :? Game as that -> this.GameAddress.Equals that.GameAddress
              | _ -> failwithumf ()
  
          override this.GetHashCode () = this.GameAddress.GetHashCode ()
  