code: func RemoteAddr(r *http.Request) string {
  	if prior := r.Header.Get("X-Forwarded-For"); prior != "" {
  		proxies := strings.Split(prior, ",")
  		if len(proxies) > 0 {
  			remoteAddr := strings.Trim(proxies[0], " ")
  			if parseIP(remoteAddr) != nil {
  				return remoteAddr
  			}
  		}
  	}
  	// X-Real-Ip is less supported, but worth checking in the
  	// absence of X-Forwarded-For
  	if realIP := r.Header.Get("X-Real-Ip"); realIP != "" {
  		if parseIP(realIP) != nil {
  			return realIP
  		}
  	}
  
  	return r.RemoteAddr
  }
docs: // RemoteAddr extracts the remote address of the request, taking into
  // account proxy headers.