#### `Optional`

`Optional` bir değişkenin `str`gibi bir tipi olabileceğini ama isteğe bağlı olarak tipinin `None` olabileceğini belirtir:

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

`str` yerine `Optional[str]` kullanmak editorün bu değerin her zaman `str` tipinde değil bazen `None` tipinde de olabileceğini belirtir ve hataları tespit etmemizde yardımcı olur.

#### Generic tipler

     */
    @Nonnull
    Optional<MojoExecution> getMojoExecution();

    /**
     * Gets the exception that caused the event (if any).
     *
     * @return the exception or {@code empty()} if none
     */
    Optional<Exception> getException();

    # o procedureSynonymHandlingType: (NotRequired - Default NONE)
    #  You can specify the handling type of procedure synonym.
    #   NONE - No handling. (default)
    #   INCLUDE - It includes procedure synonyms.
    #   SWITCH - It switches all normal procedures to procedure synonyms.
    #
    #; procedureSynonymHandlingType = NONE
    # - - - - - - - - - -/

      .assertRequestHeader("Accept-Language", "en-US")
      .assertRequestHeader("Accept-Charset", "UTF-8")
      .assertRequestHeader("If-None-Match") // No If-None-Match on the user's request.
      .assertSentRequestAtMillis(request2SentAt, request2ReceivedAt)
      .assertReceivedResponseAtMillis(request2SentAt, request2ReceivedAt)

    assertSame(CharMatcher.any(), CharMatcher.none().negate());
    assertSame(CharMatcher.none(), CharMatcher.any().negate());

    assertSame(WHATEVER, CharMatcher.any().and(WHATEVER));
    assertSame(CharMatcher.any(), CharMatcher.any().or(WHATEVER));

    assertSame(CharMatcher.none(), CharMatcher.none().and(WHATEVER));
    assertSame(WHATEVER, CharMatcher.none().or(WHATEVER));
  }

     * If no specific handler is found, returns the wildcard handler.
     *
     * @param origin the origin to look up
     * @return the CORS handler for the origin, or null if none found
     */
    public CorsHandler get(final String origin) {
        final CorsHandler handler = handerMap.get(origin);
        if (handler != null) {
            return handler;
        }

    tests, either. This causes it to fail to find AtomicLongMapTest.

    Our workaround is to tell GWT that util.concurrent and all other packages
    have prod supersource, even if they have none. GWT is happy to ignore us
    when we specify a nonexistent path.

    (I hope that this workaround does not cause its own problems in the future.)
-->
<super-source path="super"/>

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):

## Optionale Parameter

Auf die gleiche Weise können Sie optionale Query-Parameter deklarieren, indem Sie deren Defaultwert auf `None` setzen:

{* ../../docs_src/query_params/tutorial002_py310.py hl[7] *}

In diesem Fall wird der Funktionsparameter `q` optional, und standardmäßig `None` sein.

/// check

    /*
     * (non-Javadoc)
     *
     * @see
     * org.codelibs.fess.crawler.service.impl.UrlFilterService#addIncludeUrlFilter(java
     * .lang.String, java.lang.String)
     */
    @Override
    public void addIncludeUrlFilter(final String sessionId, final String url) {
        dataHelper.addIncludeUrlPattern(sessionId, url);
    }

    /*
     * (non-Javadoc)
     *
     * @see