protected function setThumbnailer(Thumbnailer $thumbnailer)
    {
    	if(!$thumbnailer instanceof Thumbnailer) {
    		throw new \Exception('The thumbnailer service given is not instance of Thumbnailer\Thumbnailer\Thumbnailer');
    	}
        $this->options['thumbnailer'] = $thumbnailer;
        
        return $this;
    }