code: func (h *Handler) Append(router *mux.Router) {
  	router.Methods(http.MethodGet, http.MethodHead).Path("/ping").
  		HandlerFunc(func(response http.ResponseWriter, request *http.Request) {
  			statusCode := http.StatusOK
  			if h.terminating {
  				statusCode = http.StatusServiceUnavailable
  			}
  			response.WriteHeader(statusCode)
  			fmt.Fprint(response, http.StatusText(statusCode))
  		})
  }
docs: // Append adds ping routes on a router.