mr: mr,
		closer: func() {
			dec.Reset(nil)
			s2DecPool.Put(dec)
			readMsgpReaderPoolPut(mr)
		},
		creator: func() error {
			v, err := mr.ReadByte()
			if err != nil {
				return err
			}
			switch v {
			case 1, 2:
			default:
				return fmt.Errorf("metacacheReader: Unknown version: %d", v)
			}
			return nil
		},
	}
}

func (r *metacacheReader) checkInit() {

	}
	defer xhttp.DrainBody(respBody)

	pr, pw := io.Pipe()
	go func() {
		pw.CloseWithError(waitForHTTPStream(respBody, pw))
	}()
	mr := msgp.NewReader(pr)
	defer readMsgpReaderPoolPut(mr)
	for {
		var file ReadMultipleResp
		if err := file.DecodeMsg(mr); err != nil {
			if errors.Is(err, io.EOF) {
				err = nil
			}
			pr.CloseWithError(err)
			return toStorageErr(err)
		}
		select {

		if r := recover(); r != nil {
			debug.PrintStack()
			rw.CloseWithError(fmt.Errorf("panic: %v", r))
		}
	}()

	var req ReadMultipleReq
	mr := msgpNewReader(r.Body)
	defer readMsgpReaderPoolPut(mr)
	err := req.DecodeMsg(mr)
	if err != nil {
		rw.CloseWithError(err)
		return
	}

	mw := msgp.NewWriter(rw)
	responses := make(chan ReadMultipleResp, len(req.Files))

```
https://yourapi.com/invoices/?callback_url=https://www.external.org/events
```

mit einem JSON-Körper:

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

dann verarbeitet *Ihre API* die Rechnung und sendet irgendwann später einen Callback-Request an die `callback_url` (die *externe API*):

```

因此，如果您的 API 用户（外部开发者）发送请求到您的 API：

```
https://yourapi.com/invoices/?callback_url=https://www.external.org/events
```

使用如下 JSON 请求体：

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

然后，您的 API 就会处理发票，并在某个点之后，发送回调请求至 `callback_url`（外部 API）：

```
https://www.external.org/events/invoices/2expen51ve
```

JSON 请求体包含如下内容：

```
https://yourapi.com/invoices/?callback_url=https://www.external.org/events
```

with a JSON body of:

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

then *your API* will process the invoice, and at some point later, send a callback request to the `callback_url` (the *external API*):

```

You might notice that to create an instance of a Python class, you use that same syntax.

For example:

```Python
class Cat:
    def __init__(self, name: str):
        self.name = name


fluffy = Cat(name="Mr Fluffy")
```

In this case, `fluffy` is an instance of the class `Cat`.

And to create `fluffy`, you are "calling" `Cat`.

So, a Python class is also a **callable**.

Zum Beispiel:

```Python
class Cat:
    def __init__(self, name: str):
        self.name = name


fluffy = Cat(name="Mr Fluffy")
```

In diesem Fall ist `fluffy` eine Instanz der Klasse `Cat`.

Und um `fluffy` zu erzeugen, rufen Sie `Cat` auf.

Eine Python-Klasse ist also auch ein **Callable**.

        function ->> execute: execute function code
        execute ->> code: return the result
    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick", salutation="Mr.")
        function ->> execute: execute function code
        execute ->> code: return the result
    end

    rect rgba(0, 255, 255, .1)
        code ->> function: say_hi(name="Rick")

        function ->> execute: führe Code der Funktion aus
        execute ->> code: gib das Resultat zurück
    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick", salutation="Mr.")
        function ->> execute: führe Code der Funktion aus
        execute ->> code: gib das Resultat zurück
    end

    rect rgba(0, 255, 255, .1)
        code ->> function: say_hi(name="Rick")