anchor.diff:  let entityModelOptActor =
       { Get = fun this ->
           match this with
  -        | Button _ | Label _ | TextBox _ | Toggle _ | Feeler _ -> None
  +        | Button _
  +        | Label _
  +        | TextBox _
  +        | Toggle _
  +        | Feeler _ -> None
           | Block block -> Some block.Actor
           | Avatar avatar -> Some avatar.Actor
           | TileMap tileMap -> Some tileMap.Actor
         Set = fun optActor this ->
           let actor = Option.get optActor
           match this with
  -        | Button _ | Label _ | TextBox _ | Toggle _ | Feeler _ -> failwith "EntityModel is not an actor."
  +        | Button _
  +        | Label _
  +        | TextBox _
  +        | Toggle _
  +        | Feeler _ -> failwith "EntityModel is not an actor."
           | Block block -> Block { block with Actor = actor }
           | Avatar avatar -> Avatar { avatar with Actor = actor }
           | TileMap tileMap -> TileMap { tileMap with Actor = actor }}
  
positive.code:       
  type [<StructuralEquality; NoComparison; CLIMutable>] TileMap =
      { Actor : Actor
        //PhysicsIds : Id list
        Density : single
        TileMapAsset : TileMapAsset
        TmxMap : TmxMap
  
negative.code:         let tmxMap = TmxMap "TileMap.tmx"
          TileMap
              { Actor = makeDefaultActor ()
                PhysicsIds = []
                Density = NormalDensity
                TileMapAsset = { TileMapAssetName = Lun.make "TileMap"; PackageName = Lun.make "Default"; PackageFileName = "AssetGraph.xml" }
                TmxMap = tmxMap
  