```Python hl_lines="3"
import os

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

/// tip | 팁

<a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 의 두 번째 인자는 반환할 기본값입니다.

여기서는 `"World"`를 넣었기에 기본값으로써 사용됩니다. 넣지 않으면 `None` 이 기본값으로 사용됩니다.

///

그러면 해당 파이썬 프로그램을 다음과 같이 호출할 수 있습니다:

■特定商取引法に基づく表示
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■よくあるお問い合わせ（FAQ）
http://www.jp.playstation.com/support/

■株式会社ソニー・コンピュータエンタテインメントの個人情報保護方針
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constraints.ParametersScriptAssert.message = Der Skriptausdruck "{script}" ist nicht wahr.
constraints.Range.message = {item} muss zwischen {min} und {max} liegen.
constraints.SafeHtml.message = {item} enthält unsicheren HTML-Inhalt.
constraints.ScriptAssert.message = Der Skriptausdruck "{script}" ist nicht wahr.
constraints.URL.message = {item} ist keine gültige URL.
constraints.Required.message = {item} ist erforderlich.

        sslSocket.enabledProtocols.intersect(tlsVersionsAsString, naturalOrder())
      } else {
        sslSocket.enabledProtocols
      }

    // In accordance with https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-00 the SCSV
    // cipher is added to signal that a protocol fallback has taken place.
    val supportedCipherSuites = sslSocket.supportedCipherSuites
    val indexOfFallbackScsv =

 * {@linkplain #close closed}. This was intended to approximately emulate the behavior of Java 7's
 * <a href="http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html"
 * >try-with-resources</a> statement in JDK6-compatible code. Code using this should be
 * approximately equivalent in behavior to the same code written with try-with-resources.
 *

    // user-specified -XX:+DisableExplicitGC.
    //
    // TODO(user): Consider using
    // java/lang/management/OperatingSystemMXBean.html#getSystemLoadAverage()
    //
    // TODO(user): Consider scaling by number of mutator threads,
    // e.g. using Thread#activeCount()
    return max(10L, Runtime.getRuntime().totalMemory() / (32L * 1024L * 1024L));
  }

{* ../../docs_src/query_params_str_validations/tutorial006.py hl[7] *}

/// info

Si vous n'avez jamais vu ce `...` auparavant : c'est une des constantes natives de Python <a href="https://docs.python.org/fr/3/library/constants.html#Ellipsis" class="external-link" target="_blank">appelée "Ellipsis"</a>.

///

Cela indiquera à **FastAPI** que la présence de ce paramètre est obligatoire.

## Liste de paramètres / valeurs multiples via Query

Then create class attributes with fixed values, which will be the available valid values:

{* ../../docs_src/path_params/tutorial005.py hl[1,6:9] *}

/// info

<a href="https://docs.python.org/3/library/enum.html" class="external-link" target="_blank">Enumerations (or enums) are available in Python</a> since version 3.4.

///

/// tip

{* ../../docs_src/path_params/tutorial005.py hl[1,6:9] *}

/// info | Información

<a href="https://docs.python.org/3/library/enum.html" class="external-link" target="_blank">Las enumeraciones (o enums) están disponibles en Python</a> desde la versión 3.4.

///

/// tip | Consejo

 * find it easier to use a framework. Frameworks automate the process, often adding features like
 * monitoring, debugging, and cancellation. Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *
 * <p>If you do chain your operations manually, you may want to use {@link FluentFuture}.
 *
 * @author Kevin Bourrillion
 * @author Nishant Thakkar
 * @author Sven Mawson