anchor.diff:      val tap: Src<'x> -> Stream<'x>
   
     /// Represents a mutable variable, called a stream variable, that generates a
  -  /// stream of values as a side-effect.
  +  /// stream of values as a side-effect.  See also: `MVar<'x>`.
   #if DOC
     ///
     /// The difference between a stream variable and a stream source is that a
  
positive.code: 
    // Introducing streams
  
    /// An empty or closed choice stream.
    ///
    /// `nil` is equivalent to `Promise.Now.withValue Nil`.
    val inline nil<'x> : Stream<'x>
  
    /// `cons x xs` constructs a choice stream whose first value is `x` and the
  
negative.code: #endif
    val switch: Stream<'x> -> Stream<'x> -> Stream<'x>
  
    /// `switchTo lhs rhs` is equivalent to `switch rhs lhs`.
  #if DOC
    ///
    /// `switchTo` is designed to be used in pipelines:
    ///
    ///> firstStream
    ///> |> switchTo otherStream
  #endif
    val switchTo: Stream<'x> -> Stream<'x> -> Stream<'x>
  
  