anchor.diff:    /// read.  See also: `indefinitely`.
     val values: Stream<'x> -> Alt<'x>
   
  -  /// Preliminary and subject to change.
  +  /// Eagerly reduces the given stream using the given job.
     val foldJob: ('s -> 'x -> #Job<'s>) -> 's -> Stream<'x> -> Job<'s>
  -  /// Preliminary and subject to change.
  +
  +  /// Eagerly reduces the given stream using the given function.
     val foldFun: ('s -> 'x -> 's) -> 's -> Stream<'x> -> Job<'s>
   
     /// `foldFromJob s sx2sJ xs` is equivalent to `foldJob sx2sJ s xs` and is
     /// often syntactically more convenient to use.
     val foldFromJob: 's -> ('s -> 'x -> #Job<'s>) -> Stream<'x> -> Job<'s>
  +
     /// `foldFromFun s sx2s xs` is equivalent to `foldFun sx2s s xs` and is often
     /// syntactically more convenient to use.
     val foldFromFun: 's -> ('s -> 'x -> 's) -> Stream<'x> -> Job<'s>
  
positive.code:   /// `once xJ` is equivalent to `indefinitely xJ |> take 1`.
    val once: Job<'x> -> Stream<'x>
  
    /// Preliminary and subject to change.
    val unfoldJob: ('s -> #Job<option<'x * 's>>) -> 's -> Stream<'x>
    /// Preliminary and subject to change.
    val unfoldFun: ('s -> option<'x * 's>) -> 's -> Stream<'x>
  
    /// Preliminary and subject to change.
    val iterateJob: ('x -> #Job<'x>) -> 'x -> Stream<'x>
    /// Preliminary and subject to change.
    val iterateFun: ('x -> 'x) -> 'x -> Stream<'x>
  
    /// Creates an infinite stream of the given value.
  
negative.code: 
    /// Returns a stream that produces elements passed through the given job
    /// whenever the given streams produces elements.
  #if DOC
    ///
    /// Reference implementation:
    ///
  