code: func (s *Server) Start() {
  	if s.URL != "" {
  		panic("Server already started")
  	}
  	if s.client == nil {
  		s.client = &http.Client{Transport: &http.Transport{}}
  	}
  	s.URL = "http://" + s.Listener.Addr().String()
  	s.wrap()
  	s.goServe()
  }
docs: // Start starts a server from NewUnstartedServer.