* and from it, import the function `get_token_header`.

That would refer to some package above `app/`, with its own file `__init__.py`, etc. But we don't have that. So, that would throw an error in our example. 🚨

But now you know how it works, so you can use relative imports in your own apps no matter how complex they are. 🤓

### Add some custom `tags`, `responses`, and `dependencies`

{!../../../docs_src/python_types/tutorial009c.py!}
```

The parameter `name` is defined as `Optional[str]`, but it is **not optional**, you cannot call the function without the parameter:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

The `name` parameter is **still required** (not *optional*) because it doesn't have a default value. Still, `name` accepts `None` as the value:

```Python

    * Setting `status_code` to `204`, `304`, or any code below `200` (1xx) will remove the body from the response.
    * This fixes an error in Uvicorn that otherwise would be thrown: `RuntimeError: Response content longer than Content-Length`.
    * This removes `fastapi.openapi.constants.STATUS_CODES_WITH_NO_BODY`, it is replaced by a function in utils.

### Translations

This will probably happen for more than one of those tabs.

🖼, ➡️ ✊ 👉 🔢:

```Python hl_lines="1  4"
{!../../../docs_src/python_types/tutorial009c.py!}
```

🔢 `name` 🔬 `Optional[str]`, ✋️ ⚫️ **🚫 📦**, 👆 🚫🔜 🤙 🔢 🍵 🔢:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

`name` 🔢 **✔** (🚫 *📦*) ↩️ ⚫️ 🚫 ✔️ 🔢 💲. , `name` 🚫 `None` 💲:

```Python
say_hi(name=None)  # This works, None is valid 🎉
```

    **FastAPI** will do the right thing with each, the same as with normal dependencies.

## A dependency with `yield` and `try`

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

{!../../../docs_src/python_types/tutorial009c.py!}
```

Tham số `name` được định nghĩa là `Optional[str]`, nhưng nó **không phải là tùy chọn**, bạn không thể gọi hàm mà không có tham số:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

Tham số `name` **vẫn được yêu cầu** (không phải là *tùy chọn*) vì nó không có giá trị mặc định. Trong khi đó, `name` chấp nhận `None` như là giá trị:

```Python