code: func (w *AtomicWriter) Write(bs []byte) (int, error) {
  	if w.err != nil {
  		return 0, w.err
  	}
  	n, err := w.next.Write(bs)
  	if err != nil {
  		w.err = err
  		w.next.Close()
  	}
  	return n, err
  }
docs: // Write is like io.Writer, but is a no-op on an already failed AtomicWriter.