if (NS_FAILED(rv = nsServiceManager::GetService(kRDFServiceCID, kIRDFServiceIID, (nsISupports**) &mRDFService))) return rv;
XULDocumentImpl::Init(void){    nsresult rv;    if (NS_FAILED(rv = NS_NewHeapArena(&mArena, nsnull)))        return rv;    // Create a namespace manager so we can manage tags    if (NS_FAILED(rv = nsComponentManager::CreateInstance(kNameSpaceManagerCID,                                                    nsnull,                                                    kINameSpaceManagerIID,                                                    (void**) &mNameSpaceManager)))        return rv;    // Keep the RDF service cached in a member variable to make using    // it a bit less painful    if (NS_FAILED(rv = nsServiceManager::GetService(kRDFServiceCID,                                                    kIRDFServiceIID,                                                    (nsISupports**) &mRDFService)))        return rv;    return NS_OK;}