public function render()
  {
    $html = parent::render();

    if (is_null($this->value)) {
      $html = str_replace('%value%', '', $html);
    } else if ($this->value) {
      $content = static::getAssetContent('true');
      $html = str_replace('%value%', $content, $html);
    } else {
      $content = static::getAssetContent('false');
      $html = str_replace('%value%', $content, $html);
    }
    return $html;
  }