anchor.diff:      let getAudioDescriptors world : AudioDescriptor rQueue =
           let componentDescriptors = getComponentAudioDescriptors world
           let worldDescriptors = [] // TODO: get audio descriptors when there are some
  -        worldDescriptors @ componentDescriptors // NOTE: pretty inefficient
  +        componentDescriptors @ worldDescriptors // NOTE: pretty inefficient
   
       /// Play the world's audio.
       let play world_ =
  
positive.code: 
      let updateTransition1 transitionModel_ =
          let transition_ = get transitionModel_ transitionLens
          let (transition_, finished) =
              if transition_.Ticks >= transition_.Lifetime then ({ transition_ with Ticks = 0 }, true)
              else ({ transition_ with Ticks = transition_.Ticks + 1 }, false)
          let transitionModel_ = set transition_ transitionModel_ transitionLens
          (transitionModel_, finished)
  
      let updateTransition update world_ : bool * World =
          let (keepRunning, world_) =
  
negative.code:         let world2 = subscribe address subscriber subscription world
          let world3 = procedure world2
          unsubscribe address subscriber world3
  
      let swallow _ _ message world =
          (handle message, true, world)
  
      let swallowLeftMouseDuringTransition started finished world =
          if not started then
              if not finished then world
              else world |> unsubscribe DownMouseLeftAddress [] |> unsubscribe UpMouseLeftAddress [] 
          else world |> subscribe DownMouseLeftAddress [] swallow |> subscribe UpMouseLeftAddress [] swallow
  
      let unregisterButton address world =
          world |>
  