Details about the `async def` syntax for *path operation functions* and some background about asynchronous code, concurrency, and parallelism.

## In a hurry?

<abbr title="too long; didn't read"><strong>TL;DR:</strong></abbr>

If you are using third party libraries that tell you to call them with `await`, like:

```Python
results = await some_library()
```

Then, declare your *path operation functions* with `async def` like:

{!../../docs_src/handling_errors/tutorial001.py!}
```

### コード内での`HTTPException`の発生

`HTTPException`は通常のPythonの例外であり、APIに関連するデータを追加したものです。

Pythonの例外なので、`return`ではなく、`raise`です。

これはまた、*path operation関数*の内部で呼び出しているユーティリティ関数の内部から`HTTPException`を発生させた場合、*path operation関数*の残りのコードは実行されず、そのリクエストを直ちに終了させ、`HTTPException`からのHTTPエラーをクライアントに送信することを意味します。

値を返す`return`よりも例外を発生させることの利点は、「依存関係とセキュリティ」のセクションでより明確になります。

	binversion "istio.io/istio/operator/version"
)

var NeverMatch = &metav1.LabelSelector{
	MatchLabels: map[string]string{
		"istio.io/deactivated": "never-match",
	},
}

var ManifestsFlagHelpStr = `Specify a path to a directory of charts and profiles
(e.g. ~/Downloads/istio-` + binversion.OperatorVersionString + `/manifests).`

// CommandParseError distinguishes an error parsing istioctl CLI arguments from an error processing

 * to the build service.
 */
interface TestFilesCleanupBuildServiceRootExtension {
    val projectStates: MapProperty<String, TestFilesCleanupProjectState>

    /**
     * Key is the path of a task, value is the possible report dirs it generates.
     */
    val taskPathToReports: MapProperty<String, List<File>>

		<Property name="root.log.level" value="${sys:fess.log.level:-warn}" />
		<Property name="log.pattern" value="%d [%t] %-5p %msg%n" />
		<Property name="log.file.basedir" value="${sys:fess.log.path:-target/logs}" />
		<Property name="backup.date.suffix" value="_%d{yyyyMMdd}" />
		<Property name="backup.max.history" value="10" />
	</Properties>

	<Appenders>

		<Property name="root.log.level" value="${sys:fess.log.level:-warn}" />
		<Property name="log.pattern" value="%d [%t] %-5p %msg%n" />
		<Property name="log.file.basedir" value="${sys:fess.log.path:-target/logs}" />
		<Property name="backup.date.suffix" value="_%d{yyyyMMdd}" />
		<Property name="backup.max.history" value="10" />
	</Properties>

	<Appenders>

import jakarta.validation.constraints.Size;

public class CacheForm {

    @Required
    @Size(max = 100)
    public String docId;

    public String[] hq;

    // for error page

    public String q;

    public String num;

    public String sort;

    public String lang;

    public Map<String, String[]> fields = new HashMap<>();

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE components PUBLIC "-//DBFLUTE//DTD LastaDi 1.0//EN"
	"http://dbflute.org/meta/lastadi10.dtd">
<components namespace="fessCrawler">
	<include path="crawler/container.xml" />

	<!-- Converts child links to normalize it. -->
	<component name="urlConvertHelper" class="org.codelibs.fess.crawler.helper.UrlConvertHelper">
	</component>

					Scheme: httpScheme,
					Path:   SlashSeparator,
				},
				Header: http.Header{
					"Authorization": []string{"Bearer 12313123"},
				},
			},
			authT: authTypeJWT,
		},
		// Test case - 3
		// Empty authorization header.
		{
			req: &http.Request{
				URL: &url.URL{
					Host:   "127.0.0.1:9000",
					Scheme: httpScheme,
					Path:   SlashSeparator,
				},
				Header: http.Header{

			}
		}
	}
}

// baseDirFromPrefix will return the base directory given an object path.
// For example an object with name prefix/folder/object.ext will return `prefix/folder/`.
func baseDirFromPrefix(prefix string) string {
	b := path.Dir(prefix)
	if b == "." || b == "./" || b == "/" {
		b = ""
	}
	if !strings.Contains(prefix, slashSeparator) {
		b = ""
	}