w.once.Do(func() {
		w.done()
	})
	return err
}

// PipeReader is similar to io.PipeReader with wait group
type PipeReader struct {
	*io.PipeReader
	wait func()
}

// CloseWithError close with supplied error the reader end
func (r *PipeReader) CloseWithError(err error) error {
	err = r.PipeReader.CloseWithError(err)
	r.wait()
	return err
}

	}
	return ErrClosedPipe
}

// A PipeReader is the read half of a pipe.
type PipeReader struct{ pipe }

// Read implements the standard Read interface:
// it reads data from the pipe, blocking until a writer
// arrives or the write end is closed.
// If the write end is closed with an error, that error is
// returned as err; otherwise err is EOF.
func (r *PipeReader) Read(data []byte) (n int, err error) {

	return &pipe{r1, w2}, &pipe{r2, w1}
}

type pipe struct {
	*io.PipeReader
	*io.PipeWriter
}

type pipeAddr int

func (pipeAddr) Network() string {
	return "pipe"
}

func (pipeAddr) String() string {
	return "pipe"
}

func (p *pipe) Close() error {
	err := p.PipeReader.Close()
	err1 := p.PipeWriter.Close()
	if err == nil {
		err = err1
	}
	return err

	// f is the currently open file used for appends.
	// Writes to f are only synchronized once Close() is called,
	// or when files are being rotated.
	f *os.File

	pw *xioutil.PipeWriter
	pr *xioutil.PipeReader
}

// Write writes p into the current file, rotating if necessary.
// Write is non-blocking, if the writer's queue is not full.
// Write is blocking otherwise.
func (w *Writer) Write(p []byte) (n int, err error) {

	default:
		err = w.w.Close()
	}
	for i := range w.buffer {
		delete(w.buffer, i)
	}
	w.wg.Wait()
	return err
}

type writerAt struct {
	w      *io.PipeWriter
	r      *io.PipeReader
	wg     *sync.WaitGroup
	buffer map[int64][]byte
	err    error

	nextOffset int64
	m          sync.Mutex
}

func (w *writerAt) WriteAt(b []byte, offset int64) (n int, err error) {
	w.m.Lock()

		{"(*LimitedReader).Read", Method, 0},
		{"(*OffsetWriter).Seek", Method, 20},
		{"(*OffsetWriter).Write", Method, 20},
		{"(*OffsetWriter).WriteAt", Method, 20},
		{"(*PipeReader).Close", Method, 0},
		{"(*PipeReader).CloseWithError", Method, 0},
		{"(*PipeReader).Read", Method, 0},
		{"(*PipeWriter).Close", Method, 0},
		{"(*PipeWriter).CloseWithError", Method, 0},
		{"(*PipeWriter).Write", Method, 0},

	const numReqs = 5
	reqBody := func(n int) string { return fmt.Sprintf("request body %d", n) }
	reqID := func(n int) string { return fmt.Sprintf("REQ-ID-%d", n) }

	send100Response := func(w *io.PipeWriter, r *io.PipeReader) {
		defer w.Close()
		defer r.Close()
		br := bufio.NewReader(r)
		n := 0
		for {
			n++
			req, err := ReadRequest(br)
			if err == io.EOF {
				return
			}
			if err != nil {

	ContextWithTimeout(ctx context.Context, d time.Duration) (context.Context, context.CancelFunc)
}

// pipe is a goroutine-safe io.Reader/io.Writer pair. It's like
// io.Pipe except there are no PipeReader/PipeWriter halves, and the
// underlying buffer is an interface. (io.Pipe is always unbuffered)
type http2pipe struct {
	mu       sync.Mutex
	c        sync.Cond       // c.L lazily initialized to &p.mu

pkg io, func Pipe() (*PipeReader, *PipeWriter)
pkg io, func ReadAtLeast(Reader, []uint8, int) (int, error)
pkg io, func ReadFull(Reader, []uint8) (int, error)
pkg io, func TeeReader(Reader, Writer) Reader
pkg io, func WriteString(Writer, string) (int, error)
pkg io, method (*LimitedReader) Read([]uint8) (int, error)
pkg io, method (*PipeReader) Close() error