// These messages appear in responses at random. The client must detect the message type and process accordingly.
//
// Header specification:
// Continuation messages contain two headers, as follows:
// https://docs.aws.amazon.com/AmazonS3/latest/API/images/s3select-frame-diagram-cont.png
//
// Payload specification:
// Continuation messages have no payload.

</p>
<p align="center">
    FastAPI 框架，高性能，易于学习，高效编码，生产可用
</p>
<p align="center">
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/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

The `Union` in `Union[str, None]` will allow your editor to give you better support and detect errors.

///

## Additional validation

We are going to enforce that even though `q` is optional, whenever it is provided, **its length doesn't exceed 50 characters**.

### Import `Query` and `Annotated`

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    FastAPI 프레임워크, 고성능, 간편한 학습, 빠른 코드 작성, 준비된 프로덕션
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<p align="center">
    FastAPI 框架，高效能，易於學習，快速開發，適用於生產環境
</p>
<p align="center">
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</p>
<p align="center">
<a href="https://github.com/fastapi/fastapi/actions?query=workflow%3ATest+event%3Apush+branch%3Amaster" target="_blank">
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    FastAPI to szybki, prosty w nauce i gotowy do użycia w produkcji framework
</p>
<p align="center">
<a href="https://github.com/fastapi/fastapi/actions?query=workflow%3ATest" target="_blank">
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    <img src="https://img.shields.io/codecov/c/github/fastapi/fastapi?color=%2334D058" alt="Coverage">