if (! mObservers.AppendObject(aObserver)) { return NS_ERROR_FAILURE; }  return NS_OK;
if (! mObservers) { nsresult rv; rv = NS_NewISupportsArray(getter_AddRefs(mObservers)); if (NS_FAILED(rv)) return rv; }  mObservers->AppendElement(aObserver); return NS_OK;
nsBookmarksService::AddObserver(nsIRDFObserver* aObserver){    if (! aObserver)        return NS_ERROR_NULL_POINTER;    if (! mObservers.AppendObject(aObserver)) {        return NS_ERROR_FAILURE;    }        return NS_OK;}