code: public function asset($path, $packageName = null)
  	{
  		$url = System::getContainer()->get('assets.packages')->getUrl($path, $packageName);
  
  		// Contao paths are relative to the <base> tag, so remove leading slashes
  		return ltrim($url, '/');
  	}
docs: Returns an asset path
  
  @param string      $path
  @param string|null $packageName
  
  @return string