anchor.diff:  
       static member relocateCharacter index coordinates gameplay =
           Gameplay.updateChessboard (Chessboard.relocateCharacter index coordinates) gameplay
  -    
  -    static member clearPickups gameplay =
  -        Gameplay.updateChessboard Chessboard.clearPickups gameplay
       
       static member removeEnemy index gameplay =
           match index with
  
positive.code:           MetaMap = MetaMap.make
            Field = field
            Chessboard = Chessboard.init field.FieldMapNp
            CharacterMoves = Map.empty
            Puppeteer = Puppeteer.initial }
  
      static member updateMetaMap updater gameplay =
          { gameplay with MetaMap = updater gameplay.MetaMap }
      
      static member updateField updater gameplay =
          { gameplay with Field = updater gameplay.Field }
      
      static member updateChessboard updater gameplay =
          { gameplay with Chessboard = updater gameplay.Chessboard }
      
      static member updateCharacterMoves updater gameplay =
          { gameplay with CharacterMoves = updater gameplay.CharacterMoves }
      
      static member updatePuppeteer updater gameplay =
          { gameplay with Puppeteer = updater gameplay.Puppeteer }
      
      static member getEnemyIndices gameplay =
          gameplay.Chessboard.EnemyIndices
  
  
negative.code:         | PlayerIndex -> Gameplay.getEnemyIndices gameplay
          | _ -> [PlayerIndex]
      
      static member getCoordinates index gameplay =
          Chessboard.getCharacterCoordinates index gameplay.Chessboard
  
  