```Python hl_lines="3"
import os

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

/// tip

<a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 的第二个参数是要返回的默认值。

如果没有提供默认值，默认为 `None`，此处我们提供了 `"World"` 作为要使用的默认值。

///

然后，您可以调用该 Python 程序：

<div class="termy">

```console
// 这里我们还没有设置环境变量
$ python main.py

import java.util.stream.Collector;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link List} whose contents will never change, with many other important properties detailed at
 * {@link ImmutableCollection}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *

    * You can also add [`Security` dependencies with `scopes`](../advanced/security/oauth2-scopes.md){.internal-link target=_blank}.

/// tip

 * the License.
 */

package com.google.common.primitives;

import jsinterop.annotations.JsMethod;
import jsinterop.annotations.JsPackage;

/** Web specializations for {@link Doubles} methods. */
public abstract class DoublesMethodsForWeb {

  @JsMethod(name = "Math.min", namespace = JsPackage.GLOBAL)
  public static native double min(double... array);

	c_ISREG  = 0100000 // Regular file
	c_ISLNK  = 0120000 // Symbolic link
	c_ISBLK  = 060000  // Block special file
	c_ISCHR  = 020000  // Character special file
	c_ISSOCK = 0140000 // Socket
)

// FileInfoHeader creates a partially-populated [Header] from fi.
// If fi describes a symlink, FileInfoHeader records link as the link target.
// If fi describes a directory, a slash is appended to the name.
//

Eles tendem a exigir configurações mais complexas, um gerenciador de fila de mensagens/tarefas, como RabbitMQ ou Redis, mas permitem que você execute tarefas em segundo plano em vários processos e, especialmente, em vários servidores.

Para ver um exemplo, verifique os [Geradores de projeto](../project-generation.md){.internal-link target=\_blank}, todos incluem celery já configurado.

## Caveat

If you need to perform heavy background computation and you don't necessarily need it to be run by the same process (for example, you don't need to share memory, variables, etc), you might benefit from using other bigger tools like <a href="https://docs.celeryq.dev" class="external-link" target="_blank">Celery</a>.

Помните, как ранее я говорил об Annotated? Он может быть использован для добавления метаданных для ваших параметров в разделе [Введение в аннотации типов Python](../python-types.md#type-hints-with-metadata-annotations){.internal-link target=_blank}?

Пришло время использовать их в FastAPI. 🚀

У нас была аннотация следующего типа:

//// tab | Python 3.10+

```Python
q: str | None = None
```

////

//// tab | Python 3.8+

        assertEquals("PrunedTag [tag=a, id=null, css=null, attrName=target, attrValue=_blank]", tags[0].toString());

        tags = PrunedTag.parse("a.link,div#123");
        assertEquals(2, tags.length);
        assertEquals("PrunedTag [tag=a, id=null, css=link, attrName=null, attrValue=null]", tags[0].toString());
        assertEquals("PrunedTag [tag=div, id=123, css=null, attrName=null, attrValue=null]", tags[1].toString());

import java.io.Flushable;
import java.io.IOException;
import junit.framework.TestCase;

/**
 * Unit tests for {@link Flushables}.
 *
 * <p>Checks proper flushing behavior, and ensures that IOExceptions on Flushable.flush() are not
 * propagated out from the {@link Flushables#flush} method if {@code swallowException} is true.
 *
 * @author Michael Lancaster
 */
public class FlushablesTest extends TestCase {