private function addStoragesSection(ArrayNodeDefinition $node)
    {
        $node
            ->children()
                ->arrayNode('storages')
                    ->addDefaultChildrenIfNoneSet('redis')
                    ->requiresAtLeastOneElement()
                    ->useAttributeAsKey('redis')
                    ->prototype('array')
                        ->children()
                            ->scalarNode('class')
                                ->defaultValue(Service\Storage\RedisStorage::class)->cannotBeEmpty()
                            ->end()
                            ->scalarNode('client')
                                ->defaultValue('sb_redis.client.default')->cannotBeEmpty()
                            ->end()
                        ->end()
                    ->end()
                ->end()
            ->end();
    }