xml:
````xml
<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services">

    <config xmlns="http://cmf.symfony.com/schema/dic/block">
        <twig>
            <cmf-embed-blocks prefix="%%%block:\"" postfix="\"%%%"
        </twig>
    </config>
</container>