// indicate a successful protocol upgrade response.
func (r *Response) isProtocolSwitch() bool {
	return isProtocolSwitchResponse(r.StatusCode, r.Header)
}

// isProtocolSwitchResponse reports whether the response code and
// response header indicate a successful protocol upgrade response.
func isProtocolSwitchResponse(code int, h Header) bool {
	return code == StatusSwitchingProtocols && isProtocolSwitchHeader(h)
}

	// See https://golang.org/issue/36381.
	delConnectionHeader := w.closeAfterReply &&
		(!keepAlivesEnabled || !hasToken(cw.header.get("Connection"), "close")) &&
		!isProtocolSwitchResponse(w.status, header)
	if delConnectionHeader {
		delHeader("Connection")
		if w.req.ProtoAtLeast(1, 1) {
			setHeader.connection = "close"
		}
	}