code: protected function renderSearchInput()
      {
          $lines = [];
          $lines[] = Html::beginTag('div', ['class' =>'ui icon search input']);
          $lines[] = Html::tag('i', '', ['class' => 'search icon']);
          $lines[] = Html::input('text', $this->getId() . '-search', '', $this->searchInputOptions);
          $lines[] = Html::endTag('div');
          $lines[] = Html::tag('div', '', ['class' => 'divider']);
          return implode("\n", $lines);
      }
docs: Renders the search input
  
  @return string the generated search input