* UnicodeEscaper}. They are heavily optimized for performance and greatly simplify the task of
 * implementing new escapers. It is strongly recommended that when implementing a new escaper you
 * extend one of these classes. If you find that you are unable to achieve the desired behavior
 * using either of these classes, please contact the Java libraries team for advice.
 *
 * <p>Popular escapers are defined as constants in classes like {@link

You can see more details in [Starlette's official docs for Background Tasks](https://www.starlette.dev/background/).

## Caveat { #caveat }

If you don't want to add a specific value but just make it optional, set the default as `None`.

But when you want to make a query parameter required, you can just not declare any default value:

{* ../../docs_src/query_params/tutorial005_py310.py hl[6:7] *}

Here the query parameter `needy` is a required query parameter of type `str`.

If you open in your browser a URL like:

```

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