code: function languageTagFromI18n( i18n, optionalFallbackLanguageTag ) {
        if( !i18n || !i18n.hasOwnProperty( 'tags' ) ) {
           return optionalFallbackLanguageTag;
        }
        return i18n.tags[ i18n.locale ] || optionalFallbackLanguageTag;
     }
docs: ///////////////////////////////////////////////////////////////////////////////////////////////////////// 
  Retrieve the language tag of the current locale from an i18n model object, such as used on the scope.
  
  @param {{locale: String, tags: Object<String, String>}} i18n
  an internationalization model, with reference to the currently active locale and a map from locales
  to language tags
  @param {*} [optionalFallbackLanguageTag]
  a language tag to use if no tags are found on the given object
  
  @return {String}
  the localized value if found, `undefined` otherwise