code: function AssertionError(actual, expected, phrase, base) {
    this.name = 'AssertionError';
    this.actual = actual;
    this.expected = expected;
    this.message = 'expected ' + objectDisplay(actual) + ' ' +
        phrase + ' ' +
      objectDisplay(expected);
  
    if (typeof actual === 'object' || typeof expected === 'object') {
      this.showDiff = true;
    }
  
    Error.captureStackTrace(this, base);
  }
docs: class to be used with fancyFail()