```Python hl_lines="3"
import os

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

/// tip

Второй аргумент <a href=«https://docs.python.org/3.8/library/os.html#os.getenv» class=«external-link» target=«_blank»>`os.getenv()`</a> - это возвращаемое по умолчанию значение.

/// info

Tüm öğreticiyi zaten okuduysanız ve türler hakkında daha fazla bilgi için geri döndüyseniz, iyi bir kaynak:<a href="https://mypy.readthedocs.io/en/latest/cheat_sheet_py3.html" class="external-link" target="_blank"> the "cheat sheet" from `mypy`</a>.

constraints.Range.message                   = {item} muss zwischen {min} und {max} liegen.
constraints.SafeHtml.message                = {item} darf unsicheres HTML enthalten.
constraints.ScriptAssert.message            = Der Skript-Ausdruck "{script}" hat kein wahres Ergebnis geliefert.
constraints.URL.message                     = {item} muss eine gültige URL sein.

```

////

## `Union` 或者 `anyOf`

响应可以声明为两种类型的 `Union` 类型，即该响应可以是两种类型中的任意类型。

在 OpenAPI 中可以使用 `anyOf` 定义。

为此，请使用 Python 标准类型提示 <a href="https://docs.python.org/3/library/typing.html#typing.Union" class="external-link" target="_blank">`typing.Union`</a>：

/// note | "笔记"

  CYGWIN*) cygwin=true ;;
  MINGW*) mingw=true;;
  Darwin*) darwin=true
    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
    if [ -z "$JAVA_HOME" ]; then
      if [ -x "/usr/libexec/java_home" ]; then
        export JAVA_HOME="`/usr/libexec/java_home`"
      else
        export JAVA_HOME="/Library/Java/Home"
      fi
    fi
    ;;

   * value is <a href="#bitEquals">bitwise equal</a> to the expected value.
   *
   * <p>May <a
   * href="http://download.oracle.com/javase/7/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

import java.security.MessageDigest;

/**
 * Implements the MD4 message digest algorithm in Java.
 * <p>
 * <b>References:</b>
 * <ol>
 *   <li> Ronald L. Rivest,
 *        "<a href="http://www.roxen.com/rfc/rfc1320.html">
 *        The MD4 Message-Digest Algorithm</a>",
 *        IETF RFC-1320 (informational).
 * </ol>
 *
 * <p><b>$Revision: 1.2 $</b>
 * @author  Raif S. Naffah
 */

 * commandline with the <code>-Dproperty.name=value</code> VM parameter
 * will override properties from the configuration file.
 * <p>
 * There are several ways to set jCIFS properties. See
 * the <a href="../overview-summary.html#scp">overview page of the API
 * documentation</a> for details.
 */

public class Config {

public static int socketCount = 0;

    /**
     * The static <code>Properties</code>.
     */

## Technische Details

Nur ein technisches Detail für die neugierigen Nerds. 🤓

In der technischen ASGI-Spezifikation ist dies Teil des <a href="https://asgi.readthedocs.io/en/latest/specs/lifespan.html" class="external-link" target="_blank">Lifespan Protokolls</a> und definiert Events namens `startup` und `shutdown`.

/// info

        versioning.setLastUpdatedTimestamp(timestamp);
        return sv;
    }

    // the format written by Maven 2
    // (https://maven.apache.org/ref/2.2.1/maven-repository-metadata/repository-metadata.html)
    private static void addSnapshotVersionLegacy(Versioning versioning, Date timestamp, int buildNumber) {
        Snapshot snapshot = new Snapshot();
        snapshot.setBuildNumber(buildNumber);