code: public function generate($blnNoMarkup=false)
  	{
  		if (TL_MODE == 'FE' && !BE_USER_LOGGED_IN && (!$this->published || ($this->start != '' && $this->start > time()) || ($this->stop != '' && $this->stop < time())))
  		{
  			return '';
  		}
  
  		$this->type = 'article';
  		$this->blnNoMarkup = $blnNoMarkup;
  
  		// Tag response
  		if (System::getContainer()->has('fos_http_cache.http.symfony_response_tagger'))
  		{
  			/** @var ResponseTagger $responseTagger */
  			$responseTagger = System::getContainer()->get('fos_http_cache.http.symfony_response_tagger');
  			$responseTagger->addTags(array('contao.db.tl_article.' . $this->id));
  		}
  
  		return parent::generate();
  	}
docs: Check whether the article is published
  
  @param boolean $blnNoMarkup
  
  @return string