anchor.diff:  
   #nowarn "40"
   
  -[<JavaScript>]
  +[<JavaScript; Pure>]
   let AwaitEvent (e: IEvent<'T>, ca: option<unit -> unit>) : C<'T> =
       checkCancel <| fun c ->
           let rec sub : System.IDisposable =
  
positive.code:             )
          ()
  
  [<JavaScript>]
  let Parallel (cs: seq<C<'T>>) : C<'T[]> =
      let cs = Array.ofSeq cs
      if cs.Length = 0 then Return [||] else
  
negative.code:     ()
      fun c -> if c.ct.IsCancellationRequested then cancel c else r c
  
  [<JavaScript; Pure>]
  let Return (x: 'T) : C<'T> =
      checkCancel <| fun c -> c.k (Ok x)
  
  [<JavaScript; Pure>]
  let Bind (r: C<'T>, f: 'T -> C<'R>) =
      checkCancel <| fun c ->
          r { 
  