message: Tidy up example
diff: @@ -51,17 +51,15 @@ async fn client_creds_do_things(spotify: &ClientCredsSpotify) {
  async fn expire_token<S: BaseClient>(spotify: &S) {
  let token_mutex = spotify.get_token();
  let mut token = token_mutex.lock().await.unwrap();
  - assert!(token.is_some());
  - token.as_mut().map(|x| {
  + let mut token = token.as_mut().expect("Token can't be empty as this point");
  // In a regular case, the token would expire with time. Here we just do
  // it manually.
  let now = Utc::now().checked_sub_signed(Duration::seconds(10));
  - x.expires_at = now;
  - x.expires_in = Duration::seconds(0);
  + token.expires_at = now;
  + token.expires_in = Duration::seconds(0);
  // We also use a garbage access token to make sure it's actually
  // refreshed.
  - x.access_token = "garbage".to_owned();
  - });
  + token.access_token = "garbage".to_owned();
  }
  async fn with_auth(creds: Credentials, oauth: OAuth, config: Config) {
  @@ -112,8 +110,10 @@ async fn main() {
  env_logger::init();
  // Enabling automatic token refreshing in the config
  - let mut config = Config::default();
  - config.token_refreshing = true;
  + let config = Config {
  + token_refreshing: true,
  + ..Default::default()
  + };
  // The default credentials from the `.env` file will be used by default.
  let creds = Credentials::from_env().unwrap();
  