MinIO supports two ways of encrypting IAM and configuration data.
You can either use KES - together with an external KMS - or, much simpler,
set the env. variable `MINIO_KMS_SECRET_KEY` and start/restart the MinIO server. For more details about KES and how
to set it up refer to our [KMS Guide](https://github.com/minio/minio/blob/master/docs/kms/README.md).

Instead of configuring an external KMS you can start with a single key by

* Any program, any code, **can only do things** when it is being **executed**. So, when there's a **process running**.
* The process can be **terminated** (or "killed") by you, or by the operating system. At that point, it stops running/being executed, and it can **no longer do things**.

## Nested Models { #nested-models }

Each attribute of a Pydantic model has a type.

But that type can itself be another Pydantic model.

So, you can declare deeply nested JSON "objects" with specific attribute names, types and validations.

All that, arbitrarily nested.

### Define a submodel { #define-a-submodel }

For example, we can define an `Image` model:

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[7:9] *}

`@lru_cache` is part of `functools` which is part of Python's standard library, you can read more about it in the [Python docs for `@lru_cache`](https://docs.python.org/3/library/functools.html#functools.lru_cache).

## Recap { #recap }

### Include the custom docs { #include-the-custom-docs }

Now you can create the *path operations* for the custom docs.

You can reuse FastAPI's internal functions to create the HTML pages for the docs, and pass them the needed arguments:

* `openapi_url`: the URL where the HTML page for the docs can get the OpenAPI schema for your API. You can use here the attribute `app.openapi_url`.
* `title`: the title of your API.

- Once object lock configuration is set to a bucket
  - New objects inherit the retention settings of the bucket object lock configuration automatically
  - Retention headers can be optionally set while uploading objects
  - Once objects are uploaded PutObjectRetention API can be called to change retention settings

#
# If foreign key does not exist in your database,
# you can set up here as virtual foreign key for DBFlute.
#
# And it's one-to-one relation if you add one fixed condition to referrer table, 
# you can set virtual foreign key with fixedCondition and fixedSuffix.
# And you can use it to view objects too.
#
# If local column name is same as foreign column name,
# you can omit the setting of localColumnName and foreignColumnName.

We could do better.

We can declare a `UserBase` model that serves as a base for our other models. And then we can make subclasses of that model that inherit its attributes (type declarations, validation, etc).

All the data conversion, validation, documentation, etc. will still work as normally.

///

## Await for messages and send messages { #await-for-messages-and-send-messages }

In your WebSocket route you can `await` for messages and send messages.

{* ../../docs_src/websockets_/tutorial001_py310.py hl[48:52] *}

You can receive and send binary, text, and JSON data.

## Try it { #try-it }

Put your code in a file `main.py` and then run your application:

<div class="termy">

// Singleton contains a pointer to T that must be set once.
// Until the value is set all Get() calls will block.
type Singleton[T any] struct {
	v   *T
	set chan struct{}
}

// NewSingleton creates a new unset singleton.
func NewSingleton[T any]() *Singleton[T] {
	return &Singleton[T]{set: make(chan struct{}), v: nil}
}

// Get will return the singleton value.
func (s *Singleton[T]) Get() *T {
	<-s.set
	return s.v
}