anchor.diff:  ///   * \['Intl.gender', String gender, (templates for female, male, other)\]
   ///   * \['Intl.select', String choice, { 'case' : template, ...} \]
   ///   * \['text alternating with ', 0 , ' indexes in the argument list'\]
  -String evaluateJsonTemplate(dynamic input, List<dynamic> args) {
  +String$orNull evaluateJsonTemplate(dynamic input, List<dynamic> args) {
     if (input == null) return null;
     if (input is String) return input;
     if (input is int) {
  
positive.code: 
    void writeTranslations(
        Iterable<TranslatedMessage> usableTranslations, String locale) {
      output.write(r"""
    Map<String, dynamic> _messages;
    Map<String, dynamic> get messages => _messages ??=
        const JsonDecoder().convert(messageText) as Map<String, dynamic>;
  """);
  
negative.code: 
    /// Holds the generated translations.
    StringBuffer output = new StringBuffer();
  
    String get orNull => nullSafety ? '?' : '';
  
    void clearOutput() {
      output = new StringBuffer();
  