### Async Context Manager { #async-context-manager }

If you check, the function is decorated with an `@asynccontextmanager`.

That converts the function into something called an "**async context manager**".

{* ../../docs_src/events/tutorial003.py hl[1,13] *}

	}

	if optimizer, ok := stmt.Dest.(StatementModifier); ok {
		optimizer.ModifyStatement(stmt)
	}

	if db.DefaultContextTimeout > 0 {
		if _, ok := stmt.Context.Deadline(); !ok {
			stmt.Context, _ = context.WithTimeout(stmt.Context, db.DefaultContextTimeout)
		}
	}

	// assign model values
	if stmt.Model == nil {
		stmt.Model = stmt.Dest
	} else if stmt.Dest == nil {
		stmt.Dest = stmt.Model

    private final Path stateDirectory;
    private final ScheduledExecutorService scheduler;
    private final CIFSContext context;
    
    public PersistentHandleManager(CIFSContext context) {
        this.context = context;
        this.handles = new ConcurrentHashMap<>();
        this.guidToHandle = new ConcurrentHashMap<>();
        this.scheduler = Executors.newScheduledThreadPool(1);

						if _, isZero := pkField.ValueOf(db.Statement.Context, rv); isZero {
							db.AddError(pkField.Set(db.Statement.Context, rv, insertID))
							insertID += pkField.AutoIncrementIncrement
						}
					}
				}
			case reflect.Struct:
				_, isZero := pkField.ValueOf(db.Statement.Context, db.Statement.ReflectValue)
				if isZero {
					db.AddError(pkField.Set(db.Statement.Context, db.Statement.ReflectValue, insertID))
				}
			}

}

func (es EncryptedString) Value(ctx context.Context, field *schema.Field, dst reflect.Value, fieldValue interface{}) (interface{}, error) {
	return "hello" + string(es), nil
}

type CustomSerializer struct {
	prefix []byte
}

func NewCustomSerializer(prefix string) *CustomSerializer {
	return &CustomSerializer{prefix: []byte(prefix)}
}

	}
}

func (c *check) mustGetIAMUserInfo(ctx context.Context, admClnt *madmin.AdminClient, accessKey string) madmin.UserInfo {
	c.Helper()
	ui, err := admClnt.GetUserInfo(ctx, accessKey)
	if err != nil {
		c.Fatalf("should be able to get user info: %v", err)
	}
	return ui
}

func (c *check) mustNotCreateIAMUser(ctx context.Context, admClnt *madmin.AdminClient) {
	c.Helper()

			for i := 0; i < stmt.ReflectValue.Len(); i++ {
				if stmt.ReflectValue.CanAddr() {
					field.Set(stmt.Context, stmt.ReflectValue.Index(i), value)
				}
			}
		}
	case reflect.Struct:
		assignValue = func(field *schema.Field, value interface{}) {
			if stmt.ReflectValue.CanAddr() {
				field.Set(stmt.Context, stmt.ReflectValue, value)
			}
		}
	default:
		assignValue = func(field *schema.Field, value interface{}) {

func benchmarkPutObjectPart(b *testing.B, instanceType string, objSize int) {
	// create a temp Erasure/FS backend.
	ctx, cancel := context.WithCancel(b.Context())
	defer cancel()
	objLayer, disks, err := prepareTestBackend(ctx, instanceType)
	if err != nil {
		b.Fatalf("Failed obtaining Temp Backend: <ERROR> %s", err)
	}

            protected FilterChain createDefaultFilterChain() {
                return (context, query, boost) -> {
                    called.set(true);
                    return QueryBuilders.boolQuery();
                };
            }
        };
        queryProcessor.init();

        QueryContext context = new QueryContext(null, false);
        MatchAllDocsQuery query = new MatchAllDocsQuery();

}

// extractMetadataFromReq extracts metadata from HTTP header and HTTP queryString.
func extractMetadataFromReq(ctx context.Context, r *http.Request) (metadata map[string]string, err error) {
	return extractMetadata(ctx, textproto.MIMEHeader(r.Form), textproto.MIMEHeader(r.Header))
}

func extractMetadata(ctx context.Context, mimesHeader ...textproto.MIMEHeader) (metadata map[string]string, err error) {
	metadata = make(map[string]string)