anchor.diff:    /**
      * Checks whether the actual value is a bool and its value is true.
      */
  +  @deprecated
     static void isTrue(var actual, [String reason = null]) {
       if (_identical(actual, true)) return;
       String msg = _getMessage(reason);
  
positive.code:           'tolerance:<$tolerance>$msg) fails');
    }
  
    static void notEquals(unexpected, actual, [String reason = null]) {
      if (unexpected != actual) return;
      String msg = _getMessage(reason);
  
negative.code:   /**
     * Checks whether [actual] is not null.
     */
    @deprecated
    static void isNotNull(actual, [String reason = null]) {
      if (null != actual) return;
      String msg = _getMessage(reason);
  