For example:

* 200: `status.HTTP_200_OK`
* 403: `status.HTTP_403_FORBIDDEN`
* etc.

It can be convenient to quickly access HTTP (and WebSocket) status codes in your app, using autocompletion for the name without having to remember the integer status codes by memory.

Read more about it in the [FastAPI docs about Response Status Code](https://fastapi.tiangolo.com/tutorial/response-status-code/).

## Example

```python

When you run **multiple processes** of the same API program, they are commonly called **workers**.

### Worker Processes and Ports

Remember from the docs [About HTTPS](https.md){.internal-link target=_blank} that only one process can be listening on one combination of port and IP address in a server?

This is still true.

* and from it, import the function `get_token_header`.

But that file doesn't exist, our dependencies are in a file at `app/dependencies.py`.

Remember how our app/file structure looks like:

<img src="/img/tutorial/bigger-applications/package.svg">

---

The two dots `..`, like in:

```Python
from ..dependencies import get_token_header
```

But you can use this space in `Annotated` to provide **FastAPI** with additional metadata about how you want your application to behave.

The important thing to remember is that **the first *type parameter*** you pass to `Annotated` is the **actual type**. The rest, is just metadata for other tools.

For now, you just need to know that `Annotated` exists, and that it's standard Python. 😎

## Use `Annotated` in the type for the `q` parameter

Remember I told you before that `Annotated` can be used to add metadata to your parameters in the [Python Types Intro](../python-types.md#type-hints-with-metadata-annotations){.internal-link target=_blank}?

<img src="/img/tutorial/path-params/image03.png">

### Working with Python *enumerations*

The value of the *path parameter* will be an *enumeration member*.

#### Compare *enumeration members*

You can compare it with the *enumeration member* in your created enum `ModelName`:

```Python hl_lines="17"
{!../../../docs_src/path_params/tutorial005.py!}
```

#### Get the *enumeration value*

    ```Python hl_lines="7"
    {!> ../../../docs_src/request_files/tutorial001.py!}
    ```

!!! info
    `File` is a class that inherits directly from `Form`.

    But remember that when you import `Query`, `Path`, `File` and others from `fastapi`, those are actually functions that return special classes.

!!! tip

{!../../../docs_src/path_params/tutorial005.py!}
```

#### Получение *значения перечисления*

Можно получить фактическое значение (в данном случае - `str`) с помощью `model_name.value` или в общем случае `your_enum_member.value`:

```Python hl_lines="20"
{!../../../docs_src/path_params/tutorial005.py!}
```

!!! tip "Подсказка"
    Значение `"lenet"` также можно получить с помощью `ModelName.lenet.value`.

*路径参数*的值是枚举的元素。

#### 比较*枚举元素*

枚举类 `ModelName` 中的*枚举元素*支持比较操作：

```Python hl_lines="17"
{!../../../docs_src/path_params/tutorial005.py!}
```

#### 获取*枚举值*

使用 `model_name.value` 或 `your_enum_member.value` 获取实际的值（本例中为**字符串**）：

```Python hl_lines="20"
{!../../../docs_src/path_params/tutorial005.py!}
```

!!! tip "提示"

    使用 `ModelName.lenet.value` 也能获取值 `"lenet"`。

#### 返回*枚举元素*

This is similar to the 200 HTTP status codes (from 200 to 299). Those "200" status codes mean that somehow there was a "success" in the request.

The status codes in the 400 range mean that there was an error from the client.

Remember all those **"404 Not Found"** errors (and jokes)?

## Use `HTTPException`

To return HTTP responses with errors to the client you use `HTTPException`.

### Import `HTTPException`

```Python hl_lines="1"