anchor.diff:          body (
               let universe = !~"universe"
               let rec loop (state:Spaceship) = messageHandler {
  -                let! msg = Message.receive None
  +                let! msg = Message.receive ()
                   let state =
                       match msg with
                       | MoveLeft -> { state with Position = { state.Position with X = (max 0 (state.Position.X - 1)) }}
  
positive.code:     Async.Start(gameLoop(), cts.Token)
  
  let stop() = 
      cts.Cancel()
negative.code:         name "universe"
          body (
              let rec loop (state:UniverseState) = messageHandler {
                  let! msg = Message.receive ()
                  let state =
                      match msg with
                      | ItemUpdate(id, x) ->
  