3. Dieses `yield from` weist die Funktion an, über das Ding namens `file_like` zu iterieren. Und dann für jeden iterierten Teil, diesen Teil so zurückzugeben, als wenn er aus dieser Generatorfunktion (`iterfile`) stammen würde.

Im Gegensatz zu einem „**Containerimage**“, bei dem es sich um den gespeicherten statischen Inhalt handelt, bezieht sich ein „**Container**“ normalerweise auf die laufende Instanz, das Ding, das **ausgeführt** wird.

	var (
		counter int
		mv      *MetaValue
		body    = `{ "bio": "bada bing bada boom", "id": 1, "name": "Charles" }
{ "bio": "bada bing bada boom", "id": 2, "name": "Charles" }
{ "bio": "bada bing bada boom", "id": 3, "name": "Charles" }
{ "bio": "bada bing bada boom", "id": 4, "name": "Charles" }
{ "bio": "bada bing bada boom", "id": 5, "name": "Charles" }
`
	)

	decoder := NewDecoder(mkReader(body), 0)

	if err == nil {
		return stmt.QueryRowContext(ctx, args...)
	}
	return &sql.Row{}
}

func (db *PreparedStmtDB) Ping() error {
	conn, err := db.GetDBConn()
	if err != nil {
		return err
	}
	return conn.Ping()
}

type PreparedStmtTX struct {
	Tx
	PreparedStmtDB *PreparedStmtDB
}

func (db *PreparedStmtTX) GetDBConn() (*sql.DB, error) {

		return false, err
	}
	return target.isActive()
}

func (target *RedisTarget) isActive() (bool, error) {
	conn := target.pool.Get()
	defer conn.Close()

	_, pingErr := conn.Do("PING")
	if pingErr != nil {
		if xnet.IsConnRefusedErr(pingErr) {
			return false, store.ErrNotConnected
		}
		return false, pingErr
	}
	return true, nil
}

		os.Exit(1)
	} else {
		sqlDB, err := DB.DB()
		if err != nil {
			log.Printf("failed to connect database, got error %v", err)
			os.Exit(1)
		}

		err = sqlDB.Ping()
		if err != nil {
			log.Printf("failed to ping sqlDB, got error %v", err)
			os.Exit(1)
		}

		RunMigrations()
	}
}

func OpenTestConnection(cfg *gorm.Config) (db *gorm.DB, err error) {
	dbDSN := os.Getenv("GORM_DSN")

          MYSQL_USER: gorm
          MYSQL_PASSWORD: gorm
          MYSQL_RANDOM_ROOT_PASSWORD: "yes"
        ports:
          - 9910:3306
        options: >-
          --health-cmd "mysqladmin ping -ugorm -pgorm"
          --health-interval 10s
          --health-start-period 10s
          --health-timeout 5s
          --health-retries 10

    steps:
    - name: Set up Go 1.x
      uses: actions/setup-go@v4

		if resp.IsError() {
			return fmt.Errorf("Create index err: %v", res)
		}
		return nil
	}
	return nil
}

func (c *esClientV7) ping(ctx context.Context, _ ElasticsearchArgs) (bool, error) {
	resp, err := c.Ping(
		c.Ping.WithContext(ctx),
	)
	if err != nil {
		return false, store.ErrNotConnected
	}
	xhttp.DrainBody(resp.Body)
	return !resp.IsError(), nil
}

const (
	// OpConnect is a connect request.
	OpConnect Op = iota + 1

	// OpConnectResponse is a response to a connect request.
	OpConnectResponse

	// OpPing is a ping request.
	// If a mux id is specified that mux is pinged.
	// Clients send ping requests.
	OpPing

	// OpPong is a OpPing response returned by the server.
	OpPong

	// OpConnectMux will connect a new mux with optional payload.
	OpConnectMux

	}
}

func (c *Connection) handlePing(ctx context.Context, m message) {
	var ping pingMsg
	if len(m.Payload) > 0 {
		_, err := ping.UnmarshalMsg(m.Payload)
		if err != nil {
			gridLogIf(ctx, err)
		}
	}
	// c.queueMsg will reuse m.Payload

	if m.MuxID == 0 {
		gridLogIf(ctx, c.queueMsg(m, &pongMsg{T: ping.T}))
		return
	}
	// Single calls do not support pinging.