## Import `Header`

First import `Header`:

//// tab | Python 3.10+

```Python hl_lines="3"
{!> ../../docs_src/header_params/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="3"
{!> ../../docs_src/header_params/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="3"
{!> ../../docs_src/header_params/tutorial001_an.py!}
```

```Python
q: Union[str, None] = None
```

Or in Python 3.10 and above:

```Python
q: str | None = None
```

For example:

//// tab | Python 3.10+

```Python hl_lines="28"
{!> ../../docs_src/body_multiple_params/tutorial004_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="28"

```Python
q: Union[str, None] = None
```

Oder in Python 3.10 und darüber:

```Python
q: str | None = None
```

Zum Beispiel:

//// tab | Python 3.10+

```Python hl_lines="27"
{!> ../../docs_src/body_multiple_params/tutorial004_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="27"

//// tab | Python 3.10+

```Python hl_lines="8-9"
{!> ../../docs_src/dependencies/tutorial005_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="8-9"
{!> ../../docs_src/dependencies/tutorial005_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="9-10"
{!> ../../docs_src/dependencies/tutorial005_an.py!}
```

//// tab | Python 3.10+

```Python hl_lines="63-66"
{!> ../../docs_src/security/tutorial005_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="63-66"
{!> ../../docs_src/security/tutorial005_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="64-67"
{!> ../../docs_src/security/tutorial005_an.py!}
```

////

Öncelikle, `Cookie`'yi projenize dahil edin:

//// tab | Python 3.10+

```Python hl_lines="3"
{!> ../../docs_src/cookie_params/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="3"
{!> ../../docs_src/cookie_params/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="3"
{!> ../../docs_src/cookie_params/tutorial001_an.py!}
```

//// tab | Python 3.10+

```Python hl_lines="1  3  12-16"
{!> ../../docs_src/extra_data_types/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="1  3  12-16"
{!> ../../docs_src/extra_data_types/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1  3  13-17"

//// tab | Python 3.9+

```Python hl_lines="17  19-21"
{!> ../../docs_src/settings/app02_an_py39/main.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="17  19-21"
{!> ../../docs_src/settings/app02_an/main.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip

//// tab | Python 3.10+

```Python hl_lines="9-14  18"
{!> ../../docs_src/header_param_models/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="9-14  18"
{!> ../../docs_src/header_param_models/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="10-15  19"

Es sollte eine `list`e von `Depends()` sein:

//// tab | Python 3.9+

```Python hl_lines="19"
{!> ../../docs_src/dependencies/tutorial006_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="18"
{!> ../../docs_src/dependencies/tutorial006_an.py!}
```

////

//// tab | Python 3.8 nicht annotiert

/// tip | "Tipp"