```

////

//// tab | Python 3.8+

```Python hl_lines="9-11  14-15  18  19  23"
{!> ../../docs_src/generate_clients/tutorial001.py!}
```

////

Notice that the *path operations* define the models they use for request payload and response payload, using the models `Item` and `ResponseMessage`.

### API Docs

# 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"

 *  JQUERY-FORM-VALIDATOR
 *
 *  @version 2.3.77
 *  @website http://formvalidator.net/
 *  @author Victor Jonsson, http://victorjonsson.se
 *  @license MIT
 */

```Python hl_lines="2  7"
{!../../docs_src/custom_response/tutorial001b.py!}
```

/// info

The parameter `response_class` will also be used to define the "media type" of the response.

In this case, the HTTP header `Content-Type` will be set to `application/json`.

And it will be documented as such in OpenAPI.

///

/// tip

message FlowDistinguisherMethod {
  // `type` is the type of flow distinguisher method
  // The supported types are "ByUser" and "ByNamespace".
  // Required.
  optional string type = 1;
}

// FlowSchema defines the schema of a group of flows. Note that a flow is made up of a set of inbound API requests with
// similar attributes and is identified by a pair of strings: the name of the FlowSchema and a "flow distinguisher".
message FlowSchema {

 *  JQUERY-FORM-VALIDATOR
 *
 *  @version 2.3.77
 *  @website http://formvalidator.net/
 *  @author Victor Jonsson, http://victorjonsson.se
 *  @license MIT
 */

 *  JQUERY-FORM-VALIDATOR
 *
 *  @version 2.3.77
 *  @website http://formvalidator.net/
 *  @author Victor Jonsson, http://victorjonsson.se
 *  @license MIT
 */

 *  JQUERY-FORM-VALIDATOR
 *
 *  @version 2.3.77
 *  @website http://formvalidator.net/
 *  @author Victor Jonsson, http://victorjonsson.se
 *  @license MIT
 */

 *  JQUERY-FORM-VALIDATOR
 *
 *  @version 2.3.77
 *  @website http://formvalidator.net/
 *  @author Victor Jonsson, http://victorjonsson.se
 *  @license MIT
 */

  // this list must have at least one matching (by name) volumeMount in one
  // container in the template. A claim in this list takes precedence over
  // any volumes in the template, with the same name.
  // TODO: Define the behavior if a claim already exists with the same name.
  // +optional
  repeated k8s.io.api.core.v1.PersistentVolumeClaim volumeClaimTemplates = 4;