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):

oat-right {\n  float: right !important;\n}\n\n.float-none {\n  float: none !important;\n}\n\n@media (min-width: 576px) {\n  .float-sm-left {\n    float: left !important;\n  }\n  .float-sm-right {\n    float: right !important;\n  }\n  .float-sm-none {\n    float: none !important;\n  }\n}\n\n@media (min-width: 768px) {\n  .float-md-left {\n    float: left !important;\n  }\n  .float-md-right {\n    float: right !important;\n  }\n  .float-md-none {\n    float: none !important;\n  }\n}\n\n@media (min-width:...

		expectedCode      int
	}{
		// If-None-Match(false) and If-Modified-Since(true)
		{
			name:            "If-None-Match1",
			ifNoneMatch:     "aa",
			ifModifiedSince: "Sun, 26 Aug 2024 02:01:00 GMT",
			objInfo:         objInfo,
			expectedFlag:    true,
			expectedCode:    304,
		},
		// If-Modified-Since(false)
		{
			name:            "If-None-Match2",
			ifNoneMatch:     "aaa",

     * @return RDMA provider instance, or null if none available
     */
    public static RdmaProvider getProvider(Configuration config) {
        String preference = config.getRdmaProvider();
        return createProvider(preference != null ? preference : "auto");
    }

    /**
     * Select the best available RDMA provider
     *
     * @return best RDMA provider, or null if none available
     */

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):

                new RequestParam[] { RequestParam.NONE, RequestParam.NO_TIMEOUT, RequestParam.NO_RETRY, RequestParam.RETAIN_PAYLOAD },
                values, "values() order should match declaration order");
    }

    // Happy path: valueOf resolves each constant name; toString equals name; ordinal is stable
    @ParameterizedTest
    @ValueSource(strings = { "NONE", "NO_TIMEOUT", "NO_RETRY", "RETAIN_PAYLOAD" })

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):

</div>

Das bedeutet, dass es **immer einen Wert** hat, der Wert kann jedoch manchmal `None` sein (oder `null` in JSON).

Das bedeutet, dass Clients, die Ihre API verwenden, nicht prüfen müssen, ob der Wert vorhanden ist oder nicht. Sie können davon ausgehen, dass das Feld immer vorhanden ist. In einigen Fällen hat es jedoch nur den Defaultwert `None`.

</div>

Esto significa que **siempre tendrá un valor**, solo que a veces el valor podría ser `None` (o `null` en JSON).

Eso significa que, los clientes que usan tu API no tienen que comprobar si el valor existe o no, pueden **asumir que el campo siempre estará allí**, pero solo que en algunos casos tendrá el valor por defecto de `None`.

La forma de describir esto en OpenAPI es marcar ese campo como **requerido**, porque siempre estará allí.

        """
        if self.cid is not None:
            fetcher = self._create_credentials_fetcher()
            return RefreshableCredentials.create_from_metadata(
                metadata=fetcher(),
                refresh_using=fetcher,
                method=self.METHOD,
            )
        else:
            return None

    def _create_credentials_fetcher(self):
        method = self.METHOD