//                                                                           =========
    private static final DataConfigDbm _instance = new DataConfigDbm();

    private DataConfigDbm() {
    }

    public static DataConfigDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final AccessTokenDbm _instance = new AccessTokenDbm();

    private AccessTokenDbm() {
    }

    public static AccessTokenDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final ScheduledJobDbm _instance = new ScheduledJobDbm();

    private ScheduledJobDbm() {
    }

    public static ScheduledJobDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final FileConfigDbm _instance = new FileConfigDbm();

    private FileConfigDbm() {
    }

    public static FileConfigDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

        }
      };

  enum NullListener implements RemovalListener<Object, Object> {
    INSTANCE;

    @Override
    public void onRemoval(RemovalNotification<Object, Object> notification) {}
  }

  enum OneWeigher implements Weigher<Object, Object> {
    INSTANCE;

    @Override
    public int weigh(Object key, Object value) {
      return 1;
    }
  }

    //                                                                           =========
    private static final WebConfigDbm _instance = new WebConfigDbm();

    private WebConfigDbm() {
    }

    public static WebConfigDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

Il suffit de traiter la requête dans un bloc `try`/`except` :

{* ../../docs_src/custom_request_and_route/tutorial002_an_py310.py hl[14,16] *}

Si une exception se produit, l'instance de `Request` sera toujours dans la portée, ce qui nous permet de lire et d'utiliser le corps de la requête lors du traitement de l'erreur :

{* ../../docs_src/custom_request_and_route/tutorial002_an_py310.py hl[17:19] *}

    //                                                                           =========
    private static final SearchLogDbm _instance = new SearchLogDbm();

    private SearchLogDbm() {
    }

    public static SearchLogDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    if (!isJava8()) {
      assertThat(defaultComparator).isInstanceOf(ArraysCompareUnsignedComparator.class);
    } else if (unsafeComparatorAvailable()) {
      assertThat(defaultComparator).isInstanceOf(UnsafeComparator.class);
    } else {
      assertThat(defaultComparator).isEqualTo(UnsignedBytes.lexicographicalComparatorJavaImpl());
    }
  }

        }
      };

  enum NullListener implements RemovalListener<Object, Object> {
    INSTANCE;

    @Override
    public void onRemoval(RemovalNotification<Object, Object> notification) {}
  }

  enum OneWeigher implements Weigher<Object, Object> {
    INSTANCE;

    @Override
    public int weigh(Object key, Object value) {
      return 1;
    }
  }