public function children($name = null)
 {
     if ($this->argument instanceof Definition) {
         $service = new ServiceElement(null, $this->argument);
         return $service->children();
     } else {
         return parent::children($name);
     }
 }
 public function addService($id, Definition $service)
 {
     $serviceXml = new ServiceElement($id, $service);
     $this->yamlArray['services'][$serviceXml->attr('id')] = $serviceXml->toYamlArray();
 }