```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | Tipp

Das zweite Argument von [`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) ist der Defaultwert, der zurückgegeben wird.

Wenn er nicht angegeben wird, ist er standardmäßig `None`. Hier geben wir „World“ als den zu verwendenden Defaultwert an.

///

Nur ein technisches Detail für die neugierigen Nerds. 🤓

In der technischen ASGI-Spezifikation ist dies Teil des [Lifespan Protokolls](https://asgi.readthedocs.io/en/latest/specs/lifespan.html) und definiert Events namens `startup` und `shutdown`.

/// info | Info

Weitere Informationen zu Starlettes `lifespan`-Handlern finden Sie in [Starlettes Lifespan-Dokumentation](https://www.starlette.dev/lifespan/).

{* ../../docs_src/middleware/tutorial001_py310.py hl[10,12:13] *}

/// tip | 豆知識

ここでは、これらのユースケースに対してより正確になり得るため、`time.time()` の代わりに [`time.perf_counter()`](https://docs.python.org/3/library/time.html#time.perf_counter) を使用しています。 🤓

///

## 複数ミドルウェアの実行順序 { #multiple-middleware-execution-order }

erenter","pointerleave","orig","related","rnoInnerhtml","rchecked","rcleanScript","manipulationTarget","disableScript","restoreScript","cloneCopyEvent","dest","udataOld","udataCur","domManip","collection","hasScripts","iNoClone","valueIsFunction","html","_evalUrl","keepData","cleanData","dataAndEvents","deepDataAndEvents","srcElements","destElements","inPage","detach","append","prepend","insertBefore","before","after","replaceWith","replaceChild","appendTo","prependTo","insertAfter","replaceAll"...

   * value is <a href="#bitEquals">bitwise equal</a> to the expected value.
   *
   * <p>May <a
   * href="https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/package-summary.html#Spurious">
   * fail spuriously</a> and does not provide ordering guarantees, so is only rarely an appropriate
   * alternative to {@code compareAndSet}.
   *
   * @param i the index
   * @param expect the expected value

Se definirá en OpenAPI con `anyOf`.

Para hacerlo, usa la anotación de tipos estándar de Python [`typing.Union`](https://docs.python.org/3/library/typing.html#typing.Union):

/// note | Nota

Невелика технічна деталь для допитливих нердів. 🤓

Під капотом, у технічній специфікації ASGI, це частина [Протоколу тривалості життя](https://asgi.readthedocs.io/en/latest/specs/lifespan.html), і там визначені події `startup` і `shutdown`.

/// info | Інформація

Ви можете прочитати більше про обробники `lifespan` у [документації Starlette про Lifespan](https://www.starlette.dev/lifespan/).

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | İpucu

[`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) fonksiyonunun ikinci argümanı, bulunamadığında döndürülecek varsayılan (default) değerdir.

Verilmezse varsayılan olarak `None` olur; burada varsayılan değer olarak `"World"` verdik.

///

    "docs_src/pydantic_v1_in_v2/tutorial003_an_py310.py",
    "docs_src/pydantic_v1_in_v2/tutorial004_an_py310.py",
]

[tool.coverage.report]
show_missing = true
sort = "-Cover"

[tool.coverage.html]
show_contexts = true

[tool.ruff.lint]
select = [
    "E",  # pycodestyle errors
    "W",  # pycodestyle warnings
    "F",  # pyflakes
    "I",  # isort
    "B",  # flake8-bugbear

labels.facet_contentLength_250kto500k=250 KB - 500 KB
labels.facet_contentLength_1mto5m=1 MB - 5 MB
labels.facet_contentLength_5m=5 MB -  
labels.facet_filetype_title=Dateityp
labels.facet_filetype_html=HTML
labels.facet_filetype_word=MS Word
labels.facet_filetype_excel=MS Excel
labels.facet_filetype_powerpoint=MS PowerPoint
labels.facet_filetype_odt=ODF Word
labels.facet_filetype_ods=ODF-Tabelle