anchor.diff:          Map.filter (fun (k : CharacterIndex) _ -> not k.IsEnemy) this.CharacterCoordinates
       
       member this.PickupItems =
  -        Map.filter (fun _ v -> v <> None) this.PassableCoordinates
  +        Map.filter (fun _ (v : FieldSpace) -> v.ContainsPickup) this.PassableCoordinates
   
       member this.EnemyCount =
           this.EnemyCoordinates.Count
  
positive.code:         Chessboard.addMove PlayerIndex move chessboard
      
      static member setPassableCoordinates _ fieldMap chessboard =
          let passableCoordinates = fieldMap.FieldTiles |> Map.filter (fun _ fieldTile -> fieldTile.TileType = Passable) |> Map.map (fun _ _ -> None)
          Chessboard.updatePassableCoordinates (constant passableCoordinates) chessboard                    
  
  type [<ReferenceEquality; NoComparison>] Gameplay =
  
negative.code:         Gameplay.updateChessboardBy Chessboard.truncatePlayerPath () () gameplay
      
      static member addHealth coordinates gameplay =
          Gameplay.updateChessboardBy Chessboard.updateCoordinatesValue FieldSpace.addHealth coordinates gameplay
  
      static member removeHealth coordinates gameplay =
          Gameplay.updateChessboardBy Chessboard.updateCoordinatesValue FieldSpace.removePickup coordinates gameplay
      
      static member clearPickups gameplay =
          Gameplay.updateChessboardBy Chessboard.clearPickups () () gameplay
  