code: public function generateStart()
      {
          $parts = [];
          $parts[] = Html::tag('div', '', ['id' => 'section-' . $this->systemId, 'class' => 'scroll-mark']);
          $parts[] = parent::generateStart();
  
          return implode('', $parts);
      }
docs: [[@doctodo method_description:generateStart]].
  
  @return [[@doctodo return_type:generateStart]] [[@doctodo return_description:generateStart]]