from collections.abc import Generator
from contextlib import contextmanager
from typing import Annotated, Any

import pytest
from fastapi import Depends, FastAPI
from fastapi.responses import StreamingResponse
from fastapi.testclient import TestClient


class Session:
    def __init__(self) -> None:
        self.data = ["foo", "bar", "baz"]
        self.open = True

    def __iter__(self) -> Generator[str, None, None]:

from collections.abc import Generator
from contextlib import contextmanager
from typing import Annotated, Any

import pytest
from fastapi import Depends, FastAPI, WebSocket
from fastapi.testclient import TestClient


class Session:
    def __init__(self) -> None:
        self.data = ["foo", "bar", "baz"]
        self.open = True

    def __iter__(self) -> Generator[str, None, None]:
        for item in self.data:

{* ../../docs_src/dependencies/tutorial010_py39.py hl[1:9,13] *}

/// tip | Tipp

Andere Möglichkeiten, einen Kontextmanager zu erstellen, sind:

* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> oder

///

/// note | Detalles técnicos

Cualquier función que sea válida para usar con:

* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> o
* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager" class="external-link" target="_blank">`@contextlib.asynccontextmanager`</a>

///

/// note | Технические детали

Любая функция, с которой можно корректно использовать:

* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> или
* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager" class="external-link" target="_blank">`@contextlib.asynccontextmanager`</a>

///

/// note | Detalhes Técnicos

Qualquer função que possa ser utilizada com:

* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> ou
* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager" class="external-link" target="_blank">`@contextlib.asynccontextmanager`</a>

///

/// note | Technical Details

Any function that is valid to use with:

* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> or
* <a href="https://docs.python.org/3/library/contextlib.html#contextlib.asynccontextmanager" class="external-link" target="_blank">`@contextlib.asynccontextmanager`</a>

* das Software Development Kit

* der `APIRouter`
* die `requirements.txt`
* das Bearer-Token
* der Breaking Change
* der Bug
* der Button
* das Callable
* der Code
* der Commit
* der Contextmanager
* die Coroutine
* die Datenbanksession
* die Festplatte
* die Domain
* die Engine
* das Fake-X
* die HTTP-GET-Methode
* das Item
* die Bibliothek
* der Lifespan
* der Lock

import dataclasses
import inspect
import sys
from collections.abc import Coroutine, Mapping, Sequence
from contextlib import AsyncExitStack, contextmanager
from copy import copy, deepcopy
from dataclasses import dataclass
from typing import (
    Annotated,
    Any,
    Callable,
    ForwardRef,
    Optional,
    Union,
    cast,
)

import anyio
from fastapi import params
from fastapi._compat import (
    ModelField,

```Python
with open("file.txt") as file:
    file.read()
```

In neueren Versionen von Python gibt es auch einen **asynchronen Kontextmanager**. Sie würden ihn mit `async with` verwenden:

```Python
async with lifespan(app):
    await do_stuff()
```