---

But for this example, we'll use a very simple HTML document with some JavaScript, all inside a long string.

This, of course, is not optimal and you wouldn't use it for production.

In production you would have one of the options above.

But it's the simplest way to focus on the server-side of WebSockets and have a working example:

## Declaring types { #declaring-types }

You just saw the main place to declare type hints. As function parameters.

This is also the main place you would use them with **FastAPI**.

### Simple types { #simple-types }

You can declare all the standard Python types, not only `str`.

You can use, for example:

* `int`
* `float`
* `bool`
* `bytes`

# First Steps { #first-steps }

The simplest FastAPI file could look like this:

{* ../../docs_src/first_steps/tutorial001_py39.py *}

Copy that to a file `main.py`.

Run the live server:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:solid">main.py</u>

  <span style="background-color:#009485"><font color="#D3D7CF"> FastAPI </font></span>  Starting development server 🚀

   * @return a hash code for the value
   */
  @InlineMe(replacement = "Short.hashCode(value)")
  @InlineMeValidationDisabled(
      "The hash code of a short is the int version of the short itself, so it's simplest to return"
          + " that.")
  public static int hashCode(short value) {
    return value;
  }

  /**
   * Returns the {@code short} value that is equal to {@code value}, if possible.
   *

   * @return a hash code for the value
   */
  @InlineMe(replacement = "Short.hashCode(value)")
  @InlineMeValidationDisabled(
      "The hash code of a short is the int version of the short itself, so it's simplest to return"
          + " that.")
  public static int hashCode(short value) {
    return value;
  }

  /**
   * Returns the {@code short} value that is equal to {@code value}, if possible.
   *

/// tip

Having the return model ensure that a value is always available and always `int` (not `None`) is very useful for the API clients, they can write much simpler code having this certainty.

Also, **automatically generated clients** will have simpler interfaces, so that the developers communicating with your API can have a much better time working with your API. 😎

///

 *
 * <p>There are three primary interfaces provided to represent graphs. In order of increasing
 * complexity they are: {@link Graph}, {@link ValueGraph}, and {@link Network}. You should generally
 * prefer the simplest interface that satisfies your use case. See the <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#choosing-the-right-graph-type">
 * "Choosing the right graph type"</a> section of the Guava User Guide for more details.

   * @return a hash code for the value
   */
  @InlineMe(replacement = "Integer.hashCode(value)")
  @InlineMeValidationDisabled(
      "The hash code of a int is the int itself, so it's simplest to return that.")
  public static int hashCode(int value) {
    return value;
  }

  /**
   * Returns the {@code int} value that is equal to {@code value}, if possible.
   *

# Simples OAuth2 com senha e Bearer { #simple-oauth2-with-password-and-bearer }

Agora vamos construir a partir do capítulo anterior e adicionar as partes que faltam para ter um fluxo de segurança completo.

## Obtenha o `username` e a `password` { #get-the-username-and-password }

É utilizado o utils de segurança da **FastAPI** para obter o `username` e a `password`.

# Simple OAuth2 con Password y Bearer { #simple-oauth2-with-password-and-bearer }

Ahora vamos a construir a partir del capítulo anterior y agregar las partes faltantes para tener un flujo de seguridad completo.

## Obtener el `username` y `password` { #get-the-username-and-password }

Vamos a usar las utilidades de seguridad de **FastAPI** para obtener el `username` y `password`.