symfony/tests/fixtures/Symfony/Components/DependencyInjection/xml/services5.xml

<?xml version="1.0" ?>

<container xmlns="http://symfony-project.org/2.0/container">
  <services>
    <service id="foo" class="FooClass">
      <argument type="service">
        <service class="BarClass">
          <argument type="service">
            <service class="BazClass">
            </service>
          </argument>
        </service>
      </argument>
    </service>
  </services>
</container>