anchor.diff:  
       type System<'w when 'w :> Freezable> with
           member this.RegisterPipedValue (ecs : 'w Ecs) = ecs.RegisterPipedValue<obj> this.PipedKey this.PipedInit
  -        member this.WithPipedValue<'a when 'a : not struct> fn (ecs : 'w Ecs) world = ecs.WithPipedValue<'a> this.PipedKey fn world
  +        member this.WithPipedValue<'a when 'a : not struct> fn (ecs : 'w Ecs) worldOpt = ecs.WithPipedValue<'a> this.PipedKey fn worldOpt
   
   [<Extension>]
   type EcsExtensions =
  
positive.code:     new (buffered, ecs) = SystemUncorrelated (typeof<'c>.Name, buffered, ecs)
  
      member this.Components with get () = components
      member this.WithComponentsBuffered (fn : 'c ArrayRef -> 'w -> 'w) world = lock componentsBuffered (fun () -> fn componentsBuffered world)
  
      member this.IndexUncorrelated index =
          if index >= freeIndex then raise (ArgumentOutOfRangeException "index")
  
negative.code:                     match subscription.Value with
                      | :? SystemCallback<obj, 'w> as objCallback ->
                          let evt = { SystemEventData = eventData :> obj; SystemPublisher = publisher }
                          objCallback evt publisher this None |> ignore<'w option>
                      | _ -> failwithumf ()) |> Vsync.AwaitTask) |>
              Vsync.Parallel
          | (false, _) -> Vsync.Parallel []
  