anchor.diff:          | Left error -> (Some error, [])
   
       let empty =
  -        { EffectName = "Empty"
  +        { EffectName = "Anonymous"
             Playback = Once
             Lifetime = 0L
             Definitions = Map.empty
  
positive.code:         | PhysicsShape (label, bodyShape, collisionCategories, collisionMask, aspects) ->
              ignore (label, bodyShape, collisionCategories, collisionMask, aspects); failwith "TODO"
          | Composite aspects ->
              ignore aspects; failwith "TODO"
  
      let eval viewType position size rotation depth color (globalEnv : Definitions) (effect : Effect) (time : int64) : string option * EffectArtifect list =
          let localTime = time % effect.Lifetime
  
negative.code:             artifact :: artifacts
          else artifacts
  
      and evalComposite viewType slice aspects time =
          evalAspects viewType slice aspects time |> snd
  
      and evalContent viewType slice content time =
          match content with
          | ExpandContent _ ->
  