header.go
func (h *RequestHeader) VisitAllCookie(f func(key, value []byte)) {
	h.parseRawHeaders()
	h.collectCookies()
	visitArgs(h.cookies, f)
}
func (h *RequestHeader) VisitAllCookie(f func(key, value []byte)) {
	h.parseRawHeaders()
	h.collectCookies()
	visitArgs(h.cookies, f)
}
// VisitAllCookie calls f for each request cookie.
//
// f must not retain references to key and/or value after returning.