instance.interceptors.request.use(
  (config) => {
    const token = TokenService.getLocalAccessToken();
    if (token) {
      // config.headers["Authorization"] = 'Bearer ' + token;  // for Spring Boot back-end
      config.headers["x-access-token"] = token; // for Node.js Express back-end
    }
    return config;
  },
  (error) => {
    return Promise.reject(error);
  }
);