code: func StartMappingProxy(bind string, h http.Handler) error {
  	s := http.Server{
  		Addr:    bind,
  		Handler: h,
  	}
  	return s.ListenAndServe()
  }
docs: // StartMappingProxy listens for incoming http connections on `bind`
  // and uses h to handle all requests.
  // This function does not return unless there is a problem (like
  // http.ListenAndServe).