# Python Types Intro

Python has support for optional "type hints" (also called "type annotations").

These **"type hints"** or annotations are a special syntax that allow declaring the <abbr title="for example: str, int, float, bool">type</abbr> of a variable.

By declaring types for your variables, editors and tools can give you better support.

    * There is a **solution** to this, however.
* There's an **extension** to the **TLS** protocol (the one handling the encryption at the TCP level, before HTTP) called **<a href="https://en.wikipedia.org/wiki/Server_Name_Indication" class="external-link" target="_blank"><abbr title="Server Name Indication">SNI</abbr></a>**.

### Technical Details: `root_path`

When you mount a sub-application as described above, FastAPI will take care of communicating the mount path for the sub-application using a mechanism from the ASGI specification called a `root_path`.

That way, the sub-application will know to use that path prefix for the docs UI.

## Create notes

Create the *path operation function* to create notes:

```Python hl_lines="61-65"
{!../../../docs_src/async_sql_databases/tutorial001.py!}
```

!!! info
    In Pydantic v1 the method was called `.dict()`, it was deprecated (but still supported) in Pydantic v2, and renamed to `.model_dump()`.

Vous attendez donc que votre crush 😍 finisse son histoire, souriez gentiment et dites que vous allez chercher les burgers ⏸.

* A particular program while it is **running** on the operating system, using the CPU, and storing things on memory. This is also called a **process**.

### What is a Process

The word **process** is normally used in a more specific way, only referring to the thing that is running in the operating system (like in the last point above):

The `oauth2_scheme` variable is an instance of `OAuth2PasswordBearer`, but it is also a "callable".

It could be called as:

```Python
oauth2_scheme(some, parameters)
```

So, it can be used with `Depends`.

### Use it

Now you can pass that `oauth2_scheme` in a dependency with `Depends`.

# 🔗 ⏮️ 🌾

FastAPI 🐕‍🦺 🔗 👈 <abbr title='sometimes also called "exit", "cleanup", "teardown", "close", "context managers", ...'>➕ 🔁 ⏮️ 🏁</abbr>.

👉, ⚙️ `yield` ↩️ `return`, &amp; ✍ ➕ 🔁 ⏮️.

!!! tip
    ⚒ 💭 ⚙️ `yield` 1️⃣ 👁 🕰.

!!! note "📡 ℹ"
    🙆 🔢 👈 ☑ ⚙️ ⏮️:

    * <a href="https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager" class="external-link" target="_blank">`@contextlib.contextmanager`</a> ⚖️

You can think of `APIRouter` as a "mini `FastAPI`" class.

All the same options are supported.

All the same `parameters`, `responses`, `dependencies`, `tags`, etc.

!!! tip
    In this example, the variable is called `router`, but you can name it however you want.

We are going to include this `APIRouter` in the main `FastAPI` app, but first, let's check the dependencies and another `APIRouter`.

## Dependencies

    * If you depended on that previous behavior, you might need to update your code. As always, make sure your tests pass before merging the upgrade.

## 0.90.1

### Upgrades