code: func (h *ResponseHeader) Cookie(cookie *Cookie) bool {
  	v := peekArgBytes(h.cookies, cookie.Key())
  	if v == nil {
  		return false
  	}
  	cookie.ParseBytes(v)
  	return true
  }
docs: // Cookie fills cookie for the given cookie.Key.
  //
  // Returns false if cookie with the given cookie.Key is missing.