code: function getLastDefinedValue(data, index) {
      for (var i = index; i > -1; i--) {
          if (typeof data[i] !== 'undefined') {
              return data[i];
          }
      }
      throw new Error('Locale data API: locale data undefined');
  }
docs: Returns the first value that is defined in an array, going backwards.
  
  To avoid repeating the same data (e.g. when "format" and "standalone" are the same) we only
  add the first one to the locale data arrays, the other ones are only defined when different.
  We use this function to retrieve the first defined value.
  
  @experimental i18n support is experimental.