public interface Location {

    /**
     * Return the line number where the current event ends,
     * returns -1 if none is available.
     * @return the current line number
     */
    int getLineNumber();

    /**
     * Return the column number where the current event ends,
     * returns -1 if none is available.
     * @return the current column number
     */
    int getColumnNumber();

    /**

(prefers-reduced-motion: reduce) {\n  .btn {\n    transition: none;\n  }\n}\n\n.btn:hover {\n  color: #212529;\n  text-decoration: none;\n}\n\n.btn:focus, .btn.focus {\n  outline: 0;\n  box-shadow: none;\n}\n\n.btn.disabled, .btn:disabled {\n  opacity: 0.65;\n  box-shadow: none;\n}\n\n.btn:not(:disabled):not(.disabled) {\n  cursor: pointer;\n}\n\n.btn:not(:disabled):not(.disabled):active, .btn:not(:disabled):not(.disabled).active {\n  box-shadow: none;\n}\n\na.btn.disabled,\nfieldset:disabled a.btn {\n  pointer-events:...

Linux-like paths MSYS uses, for example, Docker.
"""

import argparse
import os


def should_convert(var_name: str,
                   blacklist: list[str] | None,
                   whitelist_prefix: list[str] | None):
  """Check the variable name against white/black lists."""
  if blacklist and var_name in blacklist:
    return False
  if not whitelist_prefix:
    return True

```

`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+

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):

{!> ../../docs_src/python_types/tutorial008b.py!}
```

////

In both cases this means that `item` could be an `int` or a `str`.

#### Possibly `None` { #possibly-none }

You can declare that a value could have a type, like `str`, but that it could also be `None`.

In Python 3.6 and above (including Python 3.10) you can declare it by importing and using `Optional` from the `typing` module.

```Python hl_lines="1  4"

Ihr Responsemodell könnte Defaultwerte haben, wie:

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (oder `str | None = None` in Python 3.10) hat einen Defaultwert `None`.
* `tax: float = 10.5` hat einen Defaultwert `10.5`.
* `tags: List[str] = []` hat eine leere Liste als Defaultwert: `[]`.

<img src="/img/tutorial/response-model/image02.png">

## 응답 모델 인코딩 매개변수

응답 모델은 아래와 같이 기본값을 가질 수 있습니다:

{* ../../docs_src/response_model/tutorial004.py hl[11,13:14] *}

* `description: Optional[str] = None`은 기본값으로 `None`을 갖습니다.
* `tax: float = 10.5`는 기본값으로 `10.5`를 갖습니다.
* `tags: List[str] = []` 빈 리스트의 기본값으로: `[]`.

그러나 실제로 저장되지 않았을 경우 결과에서 값을 생략하고 싶을 수 있습니다.

 */
@Experimental
@Immutable
public enum DependencyScope {

    /**
     * None. Allows you to declare dependencies (for example to alter reactor build order) but in reality dependencies
     * in this scope are not part of any path scope.
     */
    NONE("none", false),

    /**
     * Undefined. When no scope is explicitly given, UNDEFINED will be used, but its meaning will depend on

/// tip | Dica

Fazer com que o modelo de retorno garanta que um valor esteja sempre disponível e sempre seja um `int` (não `None`) é muito útil para os clientes da API, eles podem escrever código muito mais simples com essa certeza.