anchor.diff:                                          evalAspects emitterAspects slice { effector with EffectTime = effector.EffectTime - timePassed })
                                       effector.History
                               | _ -> effector.History
  -                        { effector with
  -                            History = history
  -                            EffectTime = timePassed }
  +                        { effector with History = history; EffectTime = timePassed }
                       let artifacts' =
                           List.fold
                               (fun artifacts' _ ->
                                   let slice = evalAspects aspects slice effector
  -                                let artifacts'' =
  -                                    if slice.Enabled
  -                                    then evalContent content slice effector
  -                                    else []
  +                                let artifacts'' = if slice.Enabled then evalContent content slice effector else []
                                   artifacts'' @ artifacts')
                               []
                               [0 .. emitCount - 1]
  
positive.code:         let slice = { slice with Depth = slice.Depth + shift }
          evalContents contents slice effector
  
      and private evalContent content slice effector =
          match content with
          | Content.Expand (definitionName, arguments) -> evalExpand definitionName arguments slice effector
          | StaticSprite (resource, aspects, content) -> evalStaticSprite resource aspects content slice effector
          | AnimatedSprite (resource, celSize, celRun, celCount, stutter, aspects, content) -> evalAnimatedSprite resource celSize celRun celCount stutter aspects content slice effector
          | SoundEffect (resource, aspects, content)-> evalSoundEffect resource aspects content slice effector
          | Mount (Shift shift, aspects, content) -> evalMount shift aspects content slice effector
          | Repeat (Shift shift, repetition, incrementAspects, content) -> evalRepeat shift repetition incrementAspects content slice effector
          | Emit (Shift shift, Rate rate, emitterAspects, aspects, content) -> evalEmit shift rate emitterAspects aspects content effector
          | Composite (Shift shift, contents) -> evalComposite shift contents slice effector
          | Tag (name, metadata) -> [TagArtifact (name, metadata, slice)]
          | Nil -> []
  
      and private evalContents contents slice effector =
  
negative.code: 
      and private evalAspect aspect slice effector =
          match aspect with
          | Aspect.Expand (definitionName, _) ->
              match Map.tryFind definitionName effector.EffectEnv with
              | Some definition ->
                  match definition.DefinitionBody with
  