函式在 `yield` 之前的部分，會在應用啟動前先執行。

`yield` 之後的部分，會在應用結束後再執行。

### 非同步內容管理器（Async Context Manager） { #async-context-manager }

你會看到這個函式被 `@asynccontextmanager` 裝飾。

它會把函式轉換成所謂的「**非同步內容管理器（async context manager）**」。

{* ../../docs_src/events/tutorial003_py310.py hl[1,13] *}

Python 中的**內容管理器（context manager）**可以用在 `with` 陳述式中，例如 `open()` 可以作為內容管理器使用：

```Python
with open("file.txt") as file:

		// Empty Content-Md5 header.
		{mustNewSignedEmptyMD5Request(http.MethodPut, "http://127.0.0.1:9000/", 5, bytes.NewReader([]byte("hello")), t), ErrInvalidDigest},
		// Short Content-Md5 header.
		{mustNewSignedShortMD5Request(http.MethodPut, "http://127.0.0.1:9000/", 5, bytes.NewReader([]byte("hello")), t), ErrInvalidDigest},
		// When request is properly signed, but has bad Content-MD5 header.

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"context"
	"encoding/xml"
	"net/http"

	xhttp "github.com/minio/minio/internal/http"
	"github.com/minio/minio/internal/logger"
)

// writeSTSErrorResponse writes error headers
func writeSTSErrorResponse(ctx context.Context, w http.ResponseWriter, errCode STSErrorCode, err error) {
	stsErr := stsErrCodes.ToSTSErr(errCode)

        DefaultProfileActivationContext context = new DefaultProfileActivationContext();

        context.setActiveProfileIds(request.getActiveProfileIds());
        context.setInactiveProfileIds(request.getInactiveProfileIds());
        context.setSystemProperties(request.getSystemProperties());
        // enrich user properties with project packaging

			db.Statement.Settings.Delete("rows")
			db.Statement.Dest, db.Error = db.Statement.ConnPool.QueryContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)
		} else {
			db.Statement.Dest = db.Statement.ConnPool.QueryRowContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)
		}

		db.RowsAffected = -1
	}

	res, err := obj.NewMultipartUpload(context.Background(), bucketName, testObject, opts)
	if err != nil {
		// Failed to create NewMultipartUpload, abort.
		t.Fatalf("MinIO %s : <ERROR>  %s", instanceType, err)
	}
	uploadID := res.UploadID
	uploadIDCopy := uploadID

	// create an object Part, will be used to test list object parts.

        assertThat(ClassLoaderUtil.getClassLoader(TestCase.class), is(sameInstance(TestCase.class.getClassLoader())));

        final ClassLoader context = Thread.currentThread().getContextClassLoader();
        try {
            final ClassLoader cl = new URLClassLoader(new URL[0], getClass().getClassLoader());
            Thread.currentThread().setContextClassLoader(cl);

			}
		case "Key":
			z.Key, err = dc.ReadString()
			if err != nil {
				err = msgp.WrapError(err, "Key")
				return
			}
		case "Context":
			z.Context, err = dc.ReadString()
			if err != nil {
				err = msgp.WrapError(err, "Context")
				return
			}
		default:
			err = dc.Skip()
			if err != nil {
				err = msgp.WrapError(err)
				return
			}
		}
	}
	return
}

/**
 * A skeleton eventspy that does nothing other than helping implementors.
 * @since 3.0.2
 */
public abstract class AbstractEventSpy implements EventSpy {

    @Override
    public void init(Context context) throws Exception {}

    @Override
    public void onEvent(Object event) throws Exception {}

    @Override
    public void close() throws Exception {}

        this.profileActivationFilePathInterpolator = profileActivationFilePathInterpolator;
        return this;
    }

    @Override
    public boolean isActive(Profile profile, ProfileActivationContext context, ModelProblemCollector problems) {
        Activation activation = profile.getActivation();

        if (activation == null) {
            return false;
        }

        ActivationFile file = activation.getFile();