* ClosingFuture<Integer> rowsFuture2 =
   *     queryFuture.transformAsync(
   *         (closer, result) -> {
   *           FileOutputStream fos = closer.eventuallyClose(openOutputFile(), closingExecutor);
   *           return ClosingFuture.from(result.writeRowsToOutputStreamFuture(fos));
   *      },
   *      executor);
   *
   * // Result.getRowsFuture() returns a ListenableFuture (no new closeables are created).