anchor.diff:     * Specialized equality test for strings. When the strings don't match,
      * this method shows where the mismatch starts and ends.
      */
  +  @deprecated
     static void stringEquals(String expected,
                              String actual,
                              [String reason = null]) {
  
positive.code:   /**
     * Checks whether [actual] is not null.
     */
    static void isNotNull(actual, [String reason = null]) {
      if (null != actual) return;
      String msg = _getMessage(reason);
  
negative.code:    * given tolerance. If no tolerance is given, tolerance is assumed to be the
     * value 4 significant digits smaller than the value given for expected.
     */
    @deprecated
    static void approxEquals(num expected,
                             num actual,
                             [num tolerance = null,
  