anchor.diff:     *
      * If [equals] throws, the data event is replaced by an error event
      * containing the thrown error. The behavior is equivalent to the
  -   * original stream emitting the error event.
  +   * original stream emitting the error event, and it doesn't change
  +   * the what the most recently emitted data event is.
      *
      * The returned stream is a broadcast stream if this stream is.
      * If a broadcast stream is listened to more than once, each subscription
  
positive.code:   /**
     * Forwards data events while [test] is successful.
     *
     * The returned stream provides the same events as this stream as long
     * as [test] returns `true` for the event data. The stream is done
     * when either this stream is done, or when this stream first provides
     * a value that [test] doesn't accept.
     *
     * Stops listening to the stream after the accepted elements.
     *
     * Internally the method cancels its subscription after these elements. This
     * means that single-subscription (non-broadcast) streams are closed and
  
negative.code:    * Creates a new stream with the same events as this stream.
     *
     * Whenever more than [timeLimit] passes between two events from this stream,
     * the [onTimeout] function is called, which can emit further events on
     * the returned stream.
     *
     * The countdown doesn't start until the returned stream is listened to.
     * The countdown is reset every time an event is forwarded from this stream,
  