anchor.diff:      let [<Literal>] DOOR_SIZE = 5
   
       let jq = importDefault<obj> "jquery"
  -    let jcv = importDefault<obj> "jcanvas"
   
       // let renderBox className (x: int) (y: int) (w: int) (h: int) =
       //     sprintf "M%d,%d h%dv%dh%dz" x y w h -w
  
positive.code:     let main () =
          printfn "version 1"
  
          let w, h = WORLD_WIDTH, WORLD_WIDTH
          let mazeWidth = w*ROOM_SIZE + (w + 1)*DOOR_SIZE 
          let mazeHeight = h*ROOM_SIZE + (h + 1)*DOOR_SIZE
  
negative.code:         let button = jq $ ("#restart")  
  
          canvas ? width(mazeWidth) ? height(mazeHeight) |> ignore
          canvas ? clearCanvas () |> ignore
  
          button ? click(fun _ ->
              cancel ()
              cancel <- startAnimation canvas
  