nsresult result; nsCOMPtr<nsISupports> isupp = do_QueryInterface(aItem, &result); if (NS_SUCCEEDED(result)) { result = mRangeArray->AppendElement(isupp); } return result;
return mRangeArray.AppendObject(aItem) ? NS_OK : NS_ERROR_FAILURE;
nsTypedSelection::AddItem(nsIDOMRange *aItem){  if (!mRangeArray)    return NS_ERROR_FAILURE;  if (!aItem)    return NS_ERROR_NULL_POINTER;  nsresult result;  nsCOMPtr<nsISupports> isupp = do_QueryInterface(aItem, &result);  if (NS_SUCCEEDED(result)) {    result = mRangeArray->AppendElement(isupp);  }  return result;}