code: func getLink(header http.Header, rel string) string {
  	var linkExpr = regexp.MustCompile(`<(.+?)>;\s*rel="(.+?)"`)
  
  	for _, link := range header["Link"] {
  		for _, m := range linkExpr.FindAllStringSubmatch(link, -1) {
  			if len(m) != 3 {
  				continue
  			}
  			if m[2] == rel {
  				return m[1]
  			}
  		}
  	}
  	return ""
  }
docs: // getLink get a rel into the Link header