```Python
q: Union[str, None] = None
```

Ou como em Python 3.10 e versões superiores:

```Python
q: str | None = None
```

Por exemplo:

{* ../../docs_src/body_multiple_params/tutorial004_py310.py hl[26] *}

/// info | Informação

http://127.0.0.1:8000/items/?skip=20
```

🔢 💲 👆 🔢 🔜:

* `skip=20`: ↩️ 👆 ⚒ ⚫️ 📛
* `limit=10`: ↩️ 👈 🔢 💲

## 📦 🔢

🎏 🌌, 👆 💪 📣 📦 🔢 🔢, ⚒ 👫 🔢 `None`:

{* ../../docs_src/query_params/tutorial002.py hl[9] *}

👉 💼, 🔢 🔢 `q` 🔜 📦, & 🔜 `None` 🔢.

/// check

👀 👈 **FastAPI** 🙃 🥃 👀 👈 ➡ 🔢 `item_id` ➡ 🔢 & `q` 🚫,, ⚫️ 🔢 🔢.

///

## 🔢 🔢 🆎 🛠️

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):

     *
     * - If the stack overflowed after set()/setValue() stored its result, then a call to
     * setException() will be a no-op because the Future is already done.
     *
     * Both scenarios are bad: The output Future might never complete, or, if it does complete, it
     * might not run some of its listeners. The likely result is that the app will hang. (And of

 - Newly provisioned PVs by EBS plugin will no longer use the deprecated "failure-domain.beta.kubernetes.io/zone" and "failure-domain.beta.kubernetes.io/region" labels. It will use "topology.kubernetes.io/zone" and "topology.kubernetes.io/region" labels instead. ([#99130](https://github.com/kubernetes/kubernetes/pull/99130), [@ayberk](https://github.com/ayberk)) [SIG Cloud Provider, Storage and Testing]

```

`Optional[str]` ব্যবহার করা মানে হল শুধু `str` নয়, এটি হতে পারে `None`-ও, যা আপনার এডিটরকে সেই ত্রুটিগুলি শনাক্ত করতে সাহায্য করবে যেখানে আপনি ধরে নিচ্ছেন যে একটি মান সবসময় `str` হবে, অথচ এটি `None`-ও হতে পারেও।

`Optional[Something]` মূলত `Union[Something, None]`-এর একটি শর্টকাট, এবং তারা সমতুল্য।

এর মানে হল, Python 3.10-এ, আপনি টাইপগুলির ইউনিয়ন ঘোষণা করতে `Something | None` ব্যবহার করতে পারেন:

//// tab | Python 3.10+

     *
     * - If the stack overflowed after set()/setValue() stored its result, then a call to
     * setException() will be a no-op because the Future is already done.
     *
     * Both scenarios are bad: The output Future might never complete, or, if it does complete, it
     * might not run some of its listeners. The likely result is that the app will hang. (And of

		Validity:    12 * time.Hour,
		LockEnabled: true,
	}

	expiryWorker := func(wg *sync.WaitGroup, readyCh chan<- struct{}, taskCh <-chan expiryOp, gotExpired *[]ObjectToDelete) {
		defer wg.Done()
		// signal the calling goroutine that the worker is ready tor receive tasks
		close(readyCh)
		var expired []ObjectToDelete
		for t := range taskCh {
			switch v := t.(type) {
			case noncurrentVersionsTask:

- Write and Read quorum are required to be satisfied only across the erasure set for an object. Healing is also done per object within the erasure set which contains the object.

`Optional[Something]` es realmente un atajo para `Union[Something, None]`, son equivalentes.

Esto también significa que en Python 3.10, puedes usar `Something | None`:

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```