anchor.diff:  Map _default_normalize_email_options = { 'lowercase': true };
   
   
  -// convert the input to a string
  +/// convert the input to a string
   String toString(input) {
     if (input == null || (input is List && input.length == 0)) {
       input = '';
  
positive.code: }
  
  
  // canonicalize an email address
  String normalizeEmail(String email, [Map options]) {
    options = _merge(options, _default_normalize_email_options);
    if (isEmail(email) == false) {
  
negative.code: }
  
  
  /// convert the input to a date, or null if the input is not a date
  DateTime toDate(String str) {
    try {
      return DateTime.parse(str);
  