https://github.com/zicht/framework-extra-bundle/blob/4ad317e3014e1a98d9391938bbc0630ea26682d3/src/Zicht/Bundle/FrameworkExtraBundle/DependencyInjection/ZichtFrameworkExtraExtension.php#L114-L116 
framework-extra-bundle/src/Zicht/Bundle/FrameworkExtraBundle/DependencyInjection/ZichtFrameworkExtraExtension.php
Lines 114 to 116 in 4ad317e