return value + 100;
        }
    }

    /**
     * Display attributes, also know as
     * <a href="https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters">SGR
     * (Select Graphic Rendition) parameters</a>.
     */
    public enum Attribute {
        RESET(0, "RESET"),
        INTENSITY_BOLD(1, "INTENSITY_BOLD"),
        INTENSITY_FAINT(2, "INTENSITY_FAINT"),
        ITALIC(3, "ITALIC_ON"),

<p>
A function type denotes the set of all functions with the same parameter
and result types. The value of an uninitialized variable of function type
is <code>nil</code>.
</p>

<pre class="ebnf">
FunctionType   = "func" Signature .
Signature      = Parameters [ Result ] .
Result         = Parameters | Type .
Parameters     = "(" [ ParameterList [ "," ] ] ")" .

    }

    /**
     * Creates a shallow copy of this parameter.
     */
    @Override
    public Parameter clone() {
        try {
            return (Parameter) super.clone();
        } catch (CloneNotSupportedException e) {
            throw new UnsupportedOperationException(e);
        }
    }

    public org.apache.maven.api.plugin.descriptor.Parameter getParameterV4() {

func (l *List[T]) Len() int  { … }
</pre>

<h3 id="Type_parameter_declarations">Type parameter declarations</h3>

<p>
A type parameter list declares the <i>type parameters</i> of a generic function or type declaration.
The type parameter list looks like an ordinary <a href="#Function_types">function parameter list</a>
except that the type parameter names must all be present and the list is enclosed
in square brackets rather than parentheses

der wichtigste Teil ist, um einen Parameter optional zu machen, da dieses `None` der Defaultwert ist, und das ist es, was diesen Parameter **nicht erforderlich** macht.

Der Teil mit `Union[str, None]` erlaubt es Ihrem Editor, Sie besser zu unterstützen, aber er sagt FastAPI nicht, dass dieser Parameter optional ist.

///

Jetzt können wir `Query` weitere Parameter übergeben. Fangen wir mit dem `max_length` Parameter an, der auf Strings angewendet wird:

# Path Parameters and Numeric Validations

In the same way that you can declare more validations and metadata for query parameters with `Query`, you can declare the same type of validations and metadata for path parameters with `Path`.

## Import Path

First, import `Path` from `fastapi`, and import `Annotated`:

//// tab | Python 3.10+

```Python hl_lines="1  3"
{!> ../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py!}
```

# Query Parameter Models

If you have a group of **query parameters** that are related, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

## Query Parameters with a Pydantic Model

Wenn im Request ein Query-Parameter enthalten war, wird dieser in einem Hintergrundtask in das Log geschrieben.

Und dann schreibt ein weiterer Hintergrundtask, der in der *Pfadoperation-Funktion* erstellt wird, eine Nachricht unter Verwendung des Pfad-Parameters `email`.

## Technische Details

# Body - Multiple Parameters

Now that we have seen how to use `Path` and `Query`, let's see more advanced uses of request body declarations.

## Mix `Path`, `Query` and body parameters

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

//// tab | Python 3.10+

```

as it will use that `None` as the default value, and that way make the parameter **not required**.

The `Union[str, None]` part allows your editor to provide better support, but it is not what tells FastAPI that this parameter is not required.

///

Then, we can pass more parameters to `Query`. In this case, the `max_length` parameter that applies to strings:

```Python