For example, let's define a variable to be a `list` of `str`.

=== "Python 3.9+"

    Declare the variable, with the same colon (`:`) syntax.

    As the type, put `list`.

    As the list is a type that contains some internal types, you put them in square brackets:

    ```Python hl_lines="1"
    {!> ../../../docs_src/python_types/tutorial006_py39.py!}
    ```

=== "Python 3.8+"

    "UP",  # pyupgrade
]
ignore = [
    "E501",  # line too long, handled by black
    "B008",  # do not perform function calls in argument defaults
    "C901",  # too complex
    "W191",  # indentation contains tabs
]

[tool.ruff.lint.per-file-ignores]
"__init__.py" = ["F401"]
"docs_src/dependencies/tutorial007.py" = ["F821"]
"docs_src/dependencies/tutorial008.py" = ["F821"]

Sie können das Experiment mit einem abgetrennten Pfadpräfix ganz einfach lokal ausführen, indem Sie <a href="https://docs.traefik.io/" class="external-link" target="_blank">Traefik</a> verwenden.

<a href="https://github.com/containous/traefik/releases" class="external-link" target="_blank">Laden Sie Traefik herunter</a>, es ist eine einzelne Binärdatei, Sie können die komprimierte Datei extrahieren und sie direkt vom Terminal aus ausführen.

## Imagens de contêiner

Docker tem sido uma das principais ferramentas para criar e gerenciar **imagens de contêiner** e **contêineres**.

!!! info
    🚥 👆 ⚙️ Kubernetes, 👉 🔜 🎲 <a href="https://kubernetes.io/docs/concepts/workloads/pods/init-containers/" class="external-link" target="_blank">🕑 📦</a>.

🚥 👆 ⚙️ 💼 📤 🙅‍♂ ⚠ 🏃‍♂ 👈 ⏮️ 📶 **💗 🕰 🔗** (🖼 🚥 👆 🚫 🏃 💽 🛠️, ✋️ ✅ 🚥 💽 🔜), ⤴️ 👆 💪 🚮 👫 🔠 📦 ▶️️ ⏭ ▶️ 👑 🛠️.

### 👁 📦

                });
                termynals.push(termynal);
            });
    }

    function loadVisibleTermynals() {
        termynals = termynals.filter(termynal => {
            if (termynal.container.getBoundingClientRect().top - innerHeight <= 0) {
                termynal.init();
                return false;
            }
            return true;
        });
    }

But there could be cases where you want to be able to set parameters on the dependency, without having to declare many different functions or classes.

Let's imagine that we want to have a dependency that checks if the query parameter `q` contains some fixed content.

But we want to be able to parameterize that fixed content.

## A "callable" instance

In Python there's a way to make an instance of a class a "callable".

In most cases you would (and should) have a "termination proxy" handling HTTPS for you on top, this will depend on how you deploy your application, your provider might do this for you, or you might need to set it up yourself.

!!! info
    Wenn Sie Container verwenden, beispielsweise mit Docker oder Kubernetes, erzähle ich Ihnen mehr darüber im nächsten Kapitel: [FastAPI in Containern – Docker](docker.md){.internal-link target=_blank}.

    "paid": true
}
```

and it would expect a response from that *external API* with a JSON body like:

```JSON
{
    "ok": true
}
```

!!! tip
    Notice how the callback URL used contains the URL received as a query parameter in `callback_url` (`https://www.external.org/events`) and also the invoice `id` from inside of the JSON body (`2expen51ve`).

### Add the callback router