anchor.diff:    }
   }
   
  -MessageLookupByLibrary _findGeneratedMessagesFor(String locale) {
  +MessageLookupByLibrary$orNull _findGeneratedMessagesFor(String locale) {
     var actualLocale = Intl.verifiedLocale(locale, _messagesExistFor,
         onFailure: (_) => null);
     if (actualLocale == null) return null;
  
positive.code: 
    /// Holds the generated translations.
    StringBuffer output = new StringBuffer();
  
    void clearOutput() {
      output = new StringBuffer();
  
negative.code:       output.write(loadOperation);
      }
      output.write("};\n");
      output.write(
          "\nMessageLookupByLibrary$orNull _findExact(String localeName) {\n"
          "  switch (localeName) {\n");
      for (var rawLocale in allLocales) {
        var locale = Intl.canonicalizedLocale(rawLocale);
  