The `TestClient` does some magic inside to call the asynchronous FastAPI application in your normal `def` test functions, using standard pytest. But that magic doesn't work anymore when we're using it inside asynchronous functions. By running our tests asynchronously, we can no longer use the `TestClient` inside our test functions.

{* ../../docs_src/query_params_str_validations/tutorial002_an_py310.py hl[9] *}

Notice that the default value is still `None`, so the parameter is still optional.

3) If you see backticks or any other quotes inside literal text – inside `«` and `»` –  or inside blocks of literal text – inside `«««` and `»»»` – then interpret them as literal characters, do NOT interpret them as meta characters.

The above rules are in effect now.


### Definitions of terms used in this prompt

///

If you used to rely on this behavior, now you should create the resources for background tasks inside the background task itself, and use internally only data that doesn't depend on the resources of dependencies with `yield`.

* Use the `templates` you created to render and return a `TemplateResponse`, pass the name of the template, the request object, and a "context" dictionary with key-value pairs to be used inside of the Jinja2 template.

{* ../../docs_src/templates/tutorial001_py39.py hl[4,11,15:18] *}

/// note

Before FastAPI 0.108.0, Starlette 0.29.0, the `name` was the first parameter.

.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#response-object" class="external-link" target="_blank">OpenAPI Response Object</a>, you can include anything from this directly in each response inside your `responses` parameter. Including `description`, `headers`, `content` (inside of this is that you declare different media types and JSON Schemas), and `links`....

2) Do not add trailing punctuation to headings.

### Quotes

1) Prefer Ukrainian guillemets «…» for quoted terms in prose, matching existing Ukrainian docs.
2) Never change quotes inside inline code, code blocks, URLs, or file paths.

### Ellipsis

1) Keep ellipsis style consistent with existing Ukrainian docs.
2) Never change `...` in code, URLs, or CLI examples.

### Preferred translations / glossary

### Quotes and punctuation

1) Keep punctuation style consistent with existing Simplified Chinese docs (they often mix English terms like “FastAPI” with Chinese text).
2) Never change punctuation inside inline code, code blocks, URLs, or file paths.

### Ellipsis

1) Keep ellipsis style consistent within each document, prefer `...` over  `……`.
2) Never change ellipsis in code, URLs, or CLI examples.

And Swagger UI has supported this particular `examples` field for a while. So, you can use it to **show** different **examples in the docs UI**.

The shape of this OpenAPI-specific field `examples` is a `dict` with **multiple examples** (instead of a `list`), each with extra information that will be added to **OpenAPI** too.

Because it's a Python exception, you don't `return` it, you `raise` it.