protected function addPhpDocumentorExtension(
        ProjectDescriptor $project,
        Transformation $transformation,
        string $destination,
        Twig_Environment $twigEnvironment
    ): void {
        $base_extension = new Extension($project, $transformation);
        $base_extension->setDestination(
            substr($destination, strlen($transformation->getTransformer()->getTarget()) + 1)
        );
        $base_extension->setRouters($this->routers);
        $twigEnvironment->addExtension($base_extension);
    }