File: config/services.xml

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
>
    <services>
        <service id="PChess\ChessBundle\SessionChessProvider">
            <argument type="service" id="request_stack"/>
            <argument>%chess.session_name%</argument>
        </service>
        <service id="PChess\ChessBundle\SimpleChessProvider"/>
        <service id="PChess\ChessBundle\Twig\ChessExtension">
            <argument type="abstract" key="$output"/>
            <tag name="twig.extension"/>
        </service>
    </services>
</container>