anchor.diff:              Address.hash this.GameAddress
   
           interface Simulant with
  -            member this.SimulantAddress = atoa<Game, Simulant> this.GameAddress
  +            member this.SimulantAddress = simulantAddress
               end
   
           interface Game IComparable with
  
positive.code:         // check that address is of correct length for a game
          do if Address.length gameAddress <> 0 then failwith "Game address must be length of 0."
  
          /// Create a game reference.
          new () = Game (Address.empty)
  
  
negative.code:         // check that address is of correct length for a screen
          do if Address.length screenAddress <> 1 then failwith "Screen address must be length of 1."
  
          // cache the simulant address to avoid allocation
          let simulantAddress = atoa<Screen, Simulant> screenAddress
  
          /// Create a screen reference from a name string.
          new (screenName : string) = Screen (ntoa screenName)
  
  