```Python hl_lines="16-18  21-22  28-32"
{!../../docs_src/openapi_callbacks/tutorial001.py!}
```

Há 2 diferenças principais de uma *operação de rota* normal:

* Ela não necessita ter nenhum código real, porque seu aplicativo nunca chamará esse código. Ele é usado apenas para documentar a *API externa*. Então, a função poderia ter apenas `pass`.

    for (Object e : elements) {
      array[i++] = (AnEnum) e;
    }
    return create(array);
  }

  protected abstract Set<AnEnum> create(AnEnum[] elements);

  @Override
  public AnEnum[] createArray(int length) {
    return new AnEnum[length];
  }

  /** Sorts the enums according to their natural ordering. */
  @Override
  public List<AnEnum> order(List<AnEnum> insertionOrder) {
    sort(insertionOrder);

    for (Object e : elements) {
      array[i++] = (AnEnum) e;
    }
    return create(array);
  }

  protected abstract Set<AnEnum> create(AnEnum[] elements);

  @Override
  public AnEnum[] createArray(int length) {
    return new AnEnum[length];
  }

  /** Sorts the enums according to their natural ordering. */
  @Override
  public List<AnEnum> order(List<AnEnum> insertionOrder) {
    sort(insertionOrder);

        mapEntry(AnEnum.D, "April"),
        mapEntry(AnEnum.E, "May"));
  }

  @Override
  public final Map<AnEnum, String> create(Object... entries) {
    @SuppressWarnings("unchecked")
    Entry<AnEnum, String>[] array = (Entry<AnEnum, String>[]) new Entry<?, ?>[entries.length];
    int i = 0;
    for (Object o : entries) {
      @SuppressWarnings("unchecked")
      Entry<AnEnum, String> e = (Entry<AnEnum, String>) o;

  @Override
  public SampleElements<AnEnum> samples() {
    return new Enums();
  }

  @Override
  public Multiset<AnEnum> create(Object... elements) {
    AnEnum[] array = new AnEnum[elements.length];
    int i = 0;
    for (Object e : elements) {
      array[i++] = (AnEnum) e;
    }
    return create(array);
  }

  protected abstract Multiset<AnEnum> create(AnEnum[] elements);

    return suite;
  }

  public void testIteratesOnce() {
    Map<AnEnum, AnEnum> map =
        Maps.asMap(
            ImmutableSet.of(AnEnum.A),
            new Function<AnEnum, AnEnum>() {
              boolean used = false;

              @Override
              public AnEnum apply(AnEnum ae) {
                checkState(!used, "should not be applied more than once");
                used = true;

    suite.addTest(
        SetTestSuiteBuilder.using(
                new TestEnumSetGenerator() {
                  @Override
                  protected Set<AnEnum> create(AnEnum[] elements) {
                    AnEnum[] otherElements = new AnEnum[elements.length - 1];
                    arraycopy(elements, 1, otherElements, 0, otherElements.length);
                    return Sets.immutableEnumSet(elements[0], otherElements);

      super('b', 'a', 'c', 'd', 'e');
    }
  }

  public static class Enums extends SampleElements<AnEnum> {
    public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

  public static class Ints extends SampleElements<Integer> {
    public Ints() {

    @Override
    protected Map<AnEnum, String> create(Entry<AnEnum, String>[] entries) {
      EnumMap<AnEnum, String> map = new EnumMap<>(AnEnum.class);
      for (Entry<AnEnum, String> entry : entries) {
        map.put(entry.getKey(), entry.getValue());
      }
      return ImmutableMap.copyOf(map);
    }

    @Override
    public Iterable<Entry<AnEnum, String>> order(List<Entry<AnEnum, String>> insertionOrder) {

      super('b', 'a', 'c', 'd', 'e');
    }
  }

  public static class Enums extends SampleElements<AnEnum> {
    public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

  public static class Ints extends SampleElements<Integer> {
    public Ints() {