func (input *InputSerialization) IsEmpty() bool {
	return !input.unmarshaled
}

// UnmarshalXML - decodes XML data.
func (input *InputSerialization) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	// Make subtype to avoid recursive UnmarshalXML().
	type subInputSerialization InputSerialization
	parsedInput := subInputSerialization{}
	if err := d.DecodeElement(&parsedInput, &start); err != nil {
		return errMalformedXML(err)
	}

        _ * classDoc.classExtensions >> []
        def subtypes = [ "org.gradle.Subtype1", "org.gradle.Subtype2", "org.gradle.Subtype3", "org.gradle.Subtype4" ].collect {
            ClassDoc subtype = Mock()
            _ * subtype.name >> it
            subtype
        }
        _ * classDoc.subClasses >> subtypes

        when:
        def result = parse('<root/>')
        withCategories {

	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer a.CloseRespFn(resp.Body)

	return nil
}

// UnmarshalJSON - decodes JSON data.
func (a *Args) UnmarshalJSON(data []byte) error {
	// subtype to avoid recursive call to UnmarshalJSON()
	type subArgs Args
	var so subArgs

	if err := json.Unmarshal(data, &so); err != nil {
		return err
	}

	oa := Args(so)
	if oa.URL == nil || oa.URL.String() == "" {

	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer a.CloseRespFn(resp.Body)

	return nil
}

// UnmarshalJSON - decodes JSON data.
func (a *Args) UnmarshalJSON(data []byte) error {
	// subtype to avoid recursive call to UnmarshalJSON()
	type subArgs Args
	var so subArgs

	if err := json.Unmarshal(data, &so); err != nil {
		return err
	}

	oa := Args(so)

	maximumRetentionDays  = 36500
	maximumRetentionYears = 100
)

// UnmarshalXML - decodes XML data.
func (dr *DefaultRetention) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	// Make subtype to avoid recursive UnmarshalXML().
	type defaultRetention DefaultRetention
	retention := defaultRetention{}

	if err := d.DecodeElement(&retention, &start); err != nil {
		return err
	}

    }

    private fun bodyIsStreaming(response: Response): Boolean {
      val contentType = response.body.contentType()
      return contentType != null && contentType.type == "text" && contentType.subtype == "event-stream"
    }

    companion object

 *
 * <p>In addition to convenience methods, {@link TypeToken#method} and {@link TypeToken#constructor}
 * will resolve the type parameters of the method or constructor in the context of the owner type,
 * which may be a subtype of the declaring class. For example:
 *
 * <pre>{@code
 * Method getMethod = List.class.getMethod("get", int.class);
 * Invokable<List<String>, ?> invokable = new TypeToken<List<String>>() {}.method(getMethod);

 *   <li>graphs that do/don't allow self-loops
 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered
 *   <li>graphs whose edges have associated values
 * </ul>
 *
 * <p>{@code ValueGraph}, as a subtype of {@code Graph}, explicitly does not support parallel edges,
 * and forbids implementations or extensions with parallel edges. If you need parallel edges, use

   * @throws NullPointerException if any of {@code elements} is null
   */
  public static <E> ImmutableSortedSet<E> copyOf(Iterable<? extends E> elements) {
    // Hack around E not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedSetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable<?>>natural();
    return copyOf(naturalOrder, elements);

# Body - Nested Models

With **FastAPI**, you can define, validate, document, and use arbitrarily deeply nested models (thanks to Pydantic).

## List fields

You can define an attribute to be a subtype. For example, a Python `list`:

//// tab | Python 3.10+

```Python hl_lines="12"
{!> ../../docs_src/body_nested_models/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="14"