So, what we will do next is add the code to document how that *external API* should look like to receive the callback from *your API*.

* `swagger_css_url`: die URL, unter welcher der HTML-Code für Ihre Swagger-UI-Dokumentation die **CSS**-Datei abrufen kann. Dies ist die benutzerdefinierte CDN-URL.

Und genau so für ReDoc ...

{* ../../docs_src/custom_docs_ui/tutorial001.py hl[2:6,11:19,22:24,27:33] *}

/// tip | Tipp

Die *Pfadoperation* für `swagger_ui_redirect` ist ein Hilfsmittel bei der Verwendung von OAuth2.

{* ../../docs_src/path_params/tutorial001.py hl[6:7] *}

The value of the path parameter `item_id` will be passed to your function as the argument `item_id`.

So, if you run this example and go to <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a>, you will see a response of:

```JSON
{"item_id":"foo"}
```

    steps:
    - name: Checkout repository
      uses: actions/checkout@v2
      with:
        # We must fetch at least the immediate parents so that if this is
        # a pull request then we can checkout the head.
        fetch-depth: 2

    # If this run was triggered by a pull request event, then checkout

Up to here, everything would work as normally.

But then, when you open the integrated docs UI (the frontend), it would expect to get the OpenAPI schema at `/openapi.json`, instead of `/api/v1/openapi.json`.

It has the same fields as `HeroBase`, so it won't include `secret_name`.

Finally, the identity of our heroes is protected! 🥷

It also re-declares `id: int`. By doing this, we are making a **contract** with the API clients, so that they can always expect the `id` to be there and to be an `int` (it will never be `None`).

/// tip

    }

    /*
     * non-private so that our `-source 8` build doesn't need to generate a synthetic accessor
     * method, whose mention of VarHandle would upset WriteReplaceOverridesTest under Java 8.
     */
    static final VarHandle HANDLE = byteArrayViewVarHandle(long[].class, LITTLE_ENDIAN);
  }

  /**
   * The only reference to Unsafe is in this nested class. We set things up so that if

      // requested by the user. Do not allow edits so we do not go over that limit any further. If
      // the journal rebuild failed, the journal writer will not be active, meaning we will not be
      // able to record the edit, causing file leaks. In both cases, we want to retry the clean up
      // so we can get out of this state!
      cleanupQueue.schedule(cleanupTask)
      return null
    }

So we have a dedicated thread for every socket that just reads frames and dispatches them.

#
#   Important for patching:
#
#   (2) This script targets any POSIX shell, so it avoids extensions provided
#       by Bash, Ksh, etc; in particular arrays are avoided.
#
#       The "traditional" practice of packing multiple parameters into a
#       space-separated string is a well documented source of bugs and security
#       problems, so this is (mostly) avoided, by progressively accumulating