Symfony How to Translate Variable in Twig

In Symfony we can translate strings/ text in controllers and twig.

//webkul.demo.text = 'Webkul Demo Text' //written in translation file

$this->get('translator')->trans('webkul.demo.text');

//translate variable
$webkulDemoText = 'webkul.demo.text';
$this->get('translator')->trans($webkulDemoText);

In twig we use this

{% trans %}webkul.demo.text{% trans %}

Previous twig syntax will not work for variables and will show error then how can we translate any variable in twig ? For this we have to use trans as a filter