### Don't worry about style { #dont-worry-about-style }

* Don't worry too much about things like commit message styles, I will squash and merge customizing the commit manually.

* Also don't worry about style rules, there are already automatized tools checking that.

    * That's one layer **below HTTP**.
    * So, the **certificate and encryption** handling is done **before HTTP**.
* **TCP doesn't know about "domains"**. Only about IP addresses.
    * The information about the **specific domain** requested goes in the **HTTP data**.

I think `Union[SomeType, None]` is more explicit about what it means.

It's just about the words and names. But those words can affect how you and your teammates think about the code.

As an example, let's take this function:

{* ../../docs_src/python_types/tutorial009c.py hl[1,4] *}

I'll show you some concrete examples in the next chapters.

---

Then the next concepts to consider are all about the program running your actual API (e.g. Uvicorn).

## Program and Process { #program-and-process }

We will talk a lot about the running "**process**", so it's useful to have clarity about what it means, and what's the difference with the word "**program**".

### What is a Program { #what-is-a-program }

 *   <li>element extraction methods which facilitate the retrieval of certain elements (for example
 *       {@link #last})
 *   <li>query methods which answer questions about the {@code FluentIterable}'s contents (for
 *       example {@link #anyMatch})
 *   <li>conversion methods which copy the {@code FluentIterable}'s contents into a new collection
 *       or array (for example {@link #toList})

 *   <li>element extraction methods which facilitate the retrieval of certain elements (for example
 *       {@link #last})
 *   <li>query methods which answer questions about the {@code FluentIterable}'s contents (for
 *       example {@link #anyMatch})
 *   <li>conversion methods which copy the {@code FluentIterable}'s contents into a new collection
 *       or array (for example {@link #toList})

This code is something you can actually use in your application, save the password hashes in your database, etc.

We are going to start from where we left in the previous chapter and increment it.

## About JWT { #about-jwt }

JWT means "JSON Web Tokens".

It's a standard to codify a JSON object in a long dense string without spaces. It looks like this:

```

### System metrics

Metrics about the MinIO process and the node.

| Path                        | Description                                        |
|-----------------------------|----------------------------------------------------|
| `/system/cpu`               | Metrics about CPUs on the system.                  |
| `/system/drive`             | Metrics about drives on the system.                |

type AssumedRoleUser struct {
	// The ARN of the temporary security credentials that are returned from the
	// AssumeRole action. For more information about ARNs and how to use them in
	// policies, see IAM Identifiers (http://docs.aws.amazon.com/IAM/latest/UserGuide/reference_identifiers.html)
	// in Using IAM.
	//
	// Arn is a required field
	Arn string

By setting `--proxy-headers` now FastAPI would be able to redirect to the right location. 😎

```
https://mysuperapp.com/items/
```

/// tip

If you want to learn more about HTTPS, check the guide [About HTTPS](../deployment/https.md){.internal-link target=_blank}.

///

### How Proxy Forwarded Headers Work