code: public function getButtonHTML()
      {
          $link = $this->getButtonLink();
  
          $stageLink = Controller::join_links($link, '?stage=Stage');
          $liveLink = Controller::join_links($link, '?stage=Live');
  
          return '<span class="better-buttons-frontend-links">
                      <a class="better-buttons-frontend-link" target="_blank" href="' . $stageLink . '">'
                          ._t('GridFieldBetterButtons.VIEWONDRAFTSITE', 'Draft site').
                      '</a> |
                      <a class="better-buttons-frontend-link" target="_blank" href="' . $liveLink . '">'.
                          _t('GridFieldBetterButtons.VIEWONLIVESITE', 'Live site').
                      '</a></span>';
      }
docs: Generates the HTML that represents the button
  @return string