anchor.diff:                          |> renderPrimitive
                           |> maybeApp Nvg.strokeWidth width
   
  -                | "polygon" ->
  +
  +                | "polyline" ->
                       let points = n |> tryReadAttribute "points" |> withDefault ""
                       let width = n |> tryReadAttribute "stroke-width"
   
  
positive.code:                             |> maybeApp Nvg.strokeWidth width
                      else
                          Nvg.empty
  
  
                  | _ -> 
  
negative.code: 
                      Circle(V2d(cx,cy), r) |> renderPrimitive
  
                  | "ellipse" ->
  
                      let cx = n |> tryReadAttribute "cx" |> withDefault 0.0
                      let cy = n |> tryReadAttribute "cy" |> withDefault 0.0
                      let rx = n |> tryReadAttribute "rx" |> withDefault 1.0
                      let ry = n |> tryReadAttribute "ry" |> withDefault 1.0
  
                      Ellipse(V2d(cx,cy), V2d(rx,ry)) |> renderPrimitive
  
  
                  | "path" ->
                      
                      let segments = n |> tryReadAttribute "d" |> withDefault ""
  