anchor.diff:    /// Returns a stream that produces a new pair of elements whenever either one
     /// of the given pair of streams produces an element.  If one of the streams
     /// produces multiple elements before any elements are produced by the other
  -  /// stream, then those elements are skipped.
  +  /// stream, then those elements are skipped.  See also: `zip`.
     val combineLatest: Stream<'x> -> Stream<'y> -> Stream<'x * 'y>
   
     /// Returns a stream that produces the same elements as the given stream, but
  
positive.code:   ///> and merge ls rs = mergeSwap ls rs <|>* mergeSwap rs ls
  #endif
    val merge: Stream<'x> -> Stream<'x> -> Stream<'x>
    /// Preliminary and subject to change.
    val append: Stream<'x> -> Stream<'x> -> Stream<'x>
    /// Preliminary and subject to change.
    val switch: Stream<'x> -> Stream<'x> -> Stream<'x>
  
    /// Preliminary and subject to change.
    val joinWith: (Stream<'x> -> Stream<'y> -> #Stream<'y>) -> Stream<#Stream<'x>> -> Stream<'y>
  
    /// Preliminary and subject to change.
    val mapJoin: (Stream<'y> -> Stream<'z> -> #Stream<'z>) -> ('x -> #Stream<'y>) -> Stream<'x> -> Stream<'z>
  
    /// Preliminary and subject to change.
    val ambMap: ('x -> #Stream<'y>) -> Stream<'x> -> Stream<'y>
    /// Preliminary and subject to change.
    val mergeMap: ('x -> #Stream<'y>) -> Stream<'x> -> Stream<'y>
    /// Preliminary and subject to change.
    val appendMap: ('x -> #Stream<'y>) -> Stream<'x> -> Stream<'y>
    /// Preliminary and subject to change.
    val switchMap: ('x -> #Stream<'y>) -> Stream<'x> -> Stream<'y>
  
    // Skipping and taking
  
    /// Preliminary and subject to change.
    val skip: int -> Stream<'x> -> Stream<'x>
    /// Preliminary and subject to change.
    val take: int -> Stream<'x> -> Stream<'x>
  
    /// Preliminary and subject to change.
  
negative.code: 
    // Joining streams
  
    /// Of the two given streams, returns the stream that first produces an
    /// element.  See also: `ambMap`.
    val amb: Stream<'x> -> Stream<'x> -> Stream<'x>
  
    /// Returns a stream that produces elements from both of the given streams so
    /// that elements from the streams are interleaved non-deterministically in
    /// the returned stream.  See also: `mergeMap`.
  #if DOC
    ///
    /// Reference implementation:
  