anchor.diff:               -> Promise<'s> when 'sJ :> Job<'s>
   
     /// Returns a job that iterates the given job constructor over the given
  -  /// stream.
  +  /// stream.  See also: `subscribeJob`.
   #if DOC
     ///
     /// Reference implementation:
  
positive.code:   val iterJob: ('x -> #Job<unit>) -> Stream<'x> -> Job<unit>
  
    /// Returns a job that iterates the given function over the given stream.  See
    /// also: `iterJob`.
    val iterFun: ('x -> unit) -> Stream<'x> -> Job<unit>
  
    /// Returns a job that iterates over all the elements of the given stream.
    /// `iter xs` is equivalent to `iterFun ignore xs`.
    val iter: Stream<'x> -> Job<unit>
  
    /// `xs |> subscribeJob x2uJ` is equivalent to `xs |> iterJob x2uJ |> queue`.
  
negative.code:   ///> Stream.combineLatest n1s n2s
    ///> |> Stream.chooseFun (fun (n1, n2) ->
    ///>    if n1 > 0 && n2 > 0 then Some () else None)
    ///> |> Stream.subscribeFun (fun () -> printfn "That was fast!")
    ///
    /// Note that there are no special hidden mechanisms involved in the
    /// implementation of stream sources.  You can easily implement similar
  