anchor.diff:          let blend = Blend.toSdlBlendMode blend
           let image = AssetTag.generalize image
           match SdlRenderer.tryFindRenderAsset image renderer with
  -        | Some renderAsset ->
  +        | ValueSome renderAsset ->
               match renderAsset with
               | TextureAsset texture ->
                   let (_, _, _, textureSizeX, textureSizeY) = SDL.SDL_QueryTexture texture
  
positive.code:         let blend = Blend.toSdlBlendMode blend
          let flip = Flip.toSdlFlip flip
          match SdlRenderer.tryFindRenderAsset image renderer with
          | Some renderAsset ->
              match renderAsset with
              | TextureAsset texture ->
                  let (_, _, _, textureSizeX, textureSizeY) = SDL.SDL_QueryTexture texture
  
negative.code:             tileAssets |>
              Array.map (fun (tileSet, tileSetImage) ->
                  match SdlRenderer.tryFindRenderAsset (AssetTag.generalize tileSetImage) renderer with
                  | ValueSome (TextureAsset tileSetTexture) -> Some (tileSet, tileSetImage, tileSetTexture)
                  | ValueSome _ -> None
                  | ValueNone -> None) |>
              Array.definitizePlus
          if allFound then
              // OPTIMIZATION: allocating refs in a tight-loop is problematic, so pulled out here
  