code: function matchLocale(locale) {
      var found = false;
      if (!locale) return false;
      locale = locale.replace(/_/g, '-').toLowerCase();
      if (localesLookup[locale]) return localesLookup[locale];
      if (options.matchSubTags) {
        while (~locale.indexOf('-')) {
          var index = locale.lastIndexOf('-');
          locale = locale.substring(0, index);
          if (localesLookup[locale]) {
            found = localesLookup[locale];
            break;
          }
        }
      }
      return found;
    }
docs: helper function to detect locale or sublocale