* tags are computed.
   */
  fun <T : Any> tag(type: KClass<T>): T?

  /**
   * Returns the tag attached with [type] as a key, or null if no tag is attached with that key.
   *
   * The tags on a call are seeded from the [request tags][Request.tag]. This set will grow if new
   * tags are computed.
   */
  fun <T> tag(type: Class<out T>): T?

  /**

# Usage

## Single Payload Requests

Single payload requests are requests and responses that are sent in a single message.
In essence, they are `[]byte` -> `[]byte, error` functions.

It is not possible to return *both* an error and a response.

Handlers are registered on the manager using `(*Manager).RegisterSingleHandler(id HandlerID, h SingleHandlerFn, subroute ...string)`.

So, all these are different origins:

* `http://localhost`
* `https://localhost`
* `http://localhost:8080`

Even if they are all in `localhost`, they use different protocols or ports, so, they are different "origins".

## Steps { #steps }

 * prefix are called a 'section'. There are 128 code points per section.
 *
 * Ranges Data (32,612 bytes)
 * ==========================
 *
 * Each entry is 4 bytes, and represents a _range_ of code points that all share a common 14-bit
 * prefix. Entries are sorted by their complete code points.
 *
 * The 4 bytes are named b0, b1, b2 and b3. We also define these supplemental values:
 *

### Return the error { #return-the-error }

After detecting that the credentials are incorrect, return an `HTTPException` with a status code 401 (the same returned when no credentials are provided) and add the header `WWW-Authenticate` to make the browser show the login prompt again:

/// tip

You might remember that request bodies are also declared with Pydantic models.

Here **FastAPI** won't get confused because you are using `Depends`.

///

/// check

The way this dependency system is designed allows us to have different dependencies (different "dependables") that all return a `User` model.

We are not restricted to having only one dependency that can return that type of data.

       safe, it needs to re-run.

       - This is unfortunate, because actually it would be safe to declare
       the task as up-to-date, because these two files, which are based on
       the generated index.xml, are outputs, not inputs. We can be sure of
       this because they are deleted in the @BeforeEach method of the
       OsgiTest test class.

       - To enable the benefit of incremental builds, we can ask Gradle

  # source of the objects to be replicated
  source:
	type: TYPE # valid values are "minio"
	bucket: BUCKET
	prefix: PREFIX
	# NOTE: if source is remote then target must be "local"
	# endpoint: ENDPOINT
	# credentials:
	#   accessKey: ACCESS-KEY
	#   secretKey: SECRET-KEY
	#   sessionToken: SESSION-TOKEN # Available when rotating credentials are used

  # target where the objects must be replicated
  target:

# Advanced Security { #advanced-security }

## Additional Features { #additional-features }

There are some extra features to handle security apart from the ones covered in the [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

/// tip

All this might seem contrived. And it might not be very clear how is it useful yet.

These examples are intentionally simple, but show how it all works.

In the chapters about security, there are utility functions that are implemented in this same way.

If you understood all this, you already know how those utility tools for security work underneath.

///