İkisi de eşdeğer ve temelde aynıdır; ancak "**optional**" kelimesi değerin isteğe bağlı olduğunu ima eder. Oysa aslında " `None` olabilir" demektir; değer isteğe bağlı olmasa ve hâlâ zorunlu olsa bile.

Bence `Union[SomeType, None]` ne demek istediğini daha açık anlatır.

Burada mesele sadece kelimeler ve isimler. Ancak bu kelimeler sizin ve ekip arkadaşlarınızın koda bakışını etkileyebilir.

Örnek olarak şu fonksiyona bakalım:

     * class could be unloaded after the above call to `getEnumConstants` but before we call
     * `get()`, but that is vanishingly unlikely.
     */
    return ref == null ? Optional.absent() : Optional.fromNullable(enumClass.cast(ref.get()));
  }

  static String formatCompact4Digits(double value) {
    return String.format(Locale.ROOT, "%.4g", value);
  }

provide OkHttp with an HTTP request, you’re describing the request at a high-level: _“fetch me this URL with these headers.”_ For correctness and efficiency, OkHttp rewrites your request before transmitting it.

OkHttp may add headers that are absent from the original request, including `Content-Length`, `Transfer-Encoding`, `User-Agent`, `Host`, `Connection`, and `Content-Type`. It will add an `Accept-Encoding` header for transparent response compression unless the header is already present....

   *     previous entry. (If the bimap contains null values, then {@code forcePut}, like {@code
   *     put}, returns {@code null} both if the key is absent and if it is present with a null
   *     value.)
   */
  @CanIgnoreReturnValue
  @Nullable V forcePut(@ParametricNullness K key, @ParametricNullness V value);

  // Bulk Operations

  /**
   * {@inheritDoc}

Öffnen Sie Ihren Browser unter [http://127.0.0.1:8000](http://127.0.0.1:8000).

Sie sehen eine einfache Seite wie:

<img src="/img/tutorial/websockets/image01.png">

Sie können Nachrichten in das Eingabefeld tippen und absenden:

<img src="/img/tutorial/websockets/image02.png">

Und Ihre **FastAPI**-Anwendung mit WebSockets antwortet:

<img src="/img/tutorial/websockets/image03.png">

Sie können viele Nachrichten senden (und empfangen):

        array[getNumElements()]);
    // array[getNumElements() + 1] might or might not have been nulled
  }

  @CollectionSize.Require(absent = ZERO)
  public void testToArray_emptyArrayOfWrongTypeForNonEmptyCollection() {
    assertThrows(
        ArrayStoreException.class,
        () -> {
          WrongType[] array = new WrongType[0];

     * proto:server[key1=val1,key2=val2]
     * or
     * proto:[key1=val1,key2=val2]
     *
     * If a key is absent it is assumed to be 'endpoint'. Thus the
     * following are equivalent:
     * proto:\\ts0.win.net[endpoint=\pipe\srvsvc]
     * proto:ts0.win.net[\pipe\srvsvc]
     *
     * If the server is absent it is set to "127.0.0.1"
     */
    /**
     * Parses a DCERPC binding string into a DcerpcBinding object

     *
     * <p>{@link #getModuleName(Path)} is preferred when only the module name is desired,
     * because a name may be present even if the descriptor is absent. This method is for
     * cases when more information is desired, such as the set of exported packages.</p>
     *
     * @param dependency path to the dependency for which to get the module name

   for an interruption before doing a blocking call. If it is interrupted,
   it throws an `InterruptedIOException`.

## Version 1.5.2

_2014-03-17_

 * Fix bug where deleting a file that was absent from the `HttpResponseCache`
   caused an IOException.
 * Fix bug in HTTP/2 where our HPACK decoder wasn't emitting entries in
   certain eviction scenarios, leading to dropped response headers.

## Version 1.5.1

  public void testPollFirst() {
    assertEquals(a, sortedMultiset.pollFirstEntry());
    assertEquals(asList(b, c), copyToList(sortedMultiset.entrySet()));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  public void testPollFirstUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> sortedMultiset.pollFirstEntry());
  }

  @CollectionSize.Require(SEVERAL)