anchor.diff:                      ({ slice with Color = applied }, artifacts)
                   | Mount content ->
                       (slice, evalContent viewType slice history content time @ artifacts)
  +                | Repeat ->
  +                    (slice, []) // TODO: implement
                   | Emit ->
  -                    // emitted = (max time lifetimes) / stutter
  -                    //Seq.unfold
  -                    failwith "Unimplemented."
  +                    //List.map fn (slice :: history)
  +                    (slice, []) // TODO: implement
                   | Bone ->
  -                    (slice, []))
  +                    (slice, [])) // TODO: implement
               (slice, [])
               aspects
   
  
positive.code:     | Depth of TweenApplicator * Algorithm * TweenNode list
      | Color of TweenApplicator * Algorithm * Tween4Node list
      | Mount of Content
      | Emit // TODO
      | Bone // TODO
  
  
negative.code:         | AnimatedSprite (resource, celSize, celRun, celCount, stutter, aspects) ->
              evalAnimatedSprite viewType slice history resource celSize celRun celCount stutter aspects time
          | PhysicsShape (label, bodyShape, collisionCategories, collisionMask, aspects) ->
              ignore (label, bodyShape, collisionCategories, collisionMask, aspects); [] // TODO: implement
          | Composite aspects ->
              evalComposite viewType slice history aspects time
  
  