cw chunkWriter

	// handlerHeader is the Header that Handlers get access to,
	// which may be retained and mutated even after WriteHeader.
	// handlerHeader is copied into cw.header at WriteHeader
	// time, and privately mutated thereafter.
	handlerHeader Header
	calledHeader  bool // handler accessed handlerHeader via Header

	written       int64 // number of bytes written in body

}

func (w *http2responseWriter) Header() Header {
	rws := w.rws
	if rws == nil {
		panic("Header called after Handler finished")
	}
	if rws.handlerHeader == nil {
		rws.handlerHeader = make(Header)
	}
	return rws.handlerHeader
}

// checkWriteHeaderCode is a copy of net/http's checkWriteHeaderCode.
func http2checkWriteHeaderCode(code int) {

		return http.Header{}
	}

	return tw.handlerHeaders
}

func (tw *baseTimeoutWriter) Write(p []byte) (int, error) {
	tw.mu.Lock()
	defer tw.mu.Unlock()

	if tw.timedOut {
		return 0, http.ErrHandlerTimeout
	}
	if tw.hijacked {
		return 0, http.ErrHijacked
	}

	if !tw.wroteHeader {
		copyHeaders(tw.w.Header(), tw.handlerHeaders)
		tw.wroteHeader = true
	}
	return tw.w.Write(p)