`Header` has a little extra functionality on top of what `Path`, `Query` and `Cookie` provide.

Most of the standard headers are separated by a "hyphen" character, also known as the "minus symbol" (`-`).

But a variable like `user-agent` is invalid in Python.

So, by default, `Header` will convert the parameter names characters from underscore (`_`) to hyphen (`-`) to extract and document the headers.

     * @param {number} options.typeDelay - Delay between each typed character, in ms.
     * @param {number} options.lineDelay - Delay between each line, in ms.
     * @param {number} options.progressLength - Number of characters displayed as progress bar.
     * @param {string} options.progressChar – Character to use for progress bar, defaults to █.
	 * @param {number} options.progressPercent - Max percent of progress.

        // Test with commands containing special characters
        final List<String> specialCommands = Arrays.asList("echo \"test with quotes\"", "echo 'test with single quotes'",
                "echo test with spaces", "echo test&with&ampersand", "echo test|with|pipe");

        generator.setCommandList(specialCommands);
        assertTrue("Special character commands should be settable", true);

{* ../../docs_src/query_params_str_validations/tutorial004_an_py310.py hl[11] *}

This specific regular expression pattern checks that the received parameter value:

* `^`: starts with the following characters, doesn't have characters before.

`secrets.compare_digest()` needs to take `bytes` or a `str` that only contains ASCII characters (the ones in English), this means it wouldn't work with characters like `á`, as in `Sebastián`.

To handle that, we first convert the `username` and `password` to `bytes` encoding them with UTF-8.

            "input": "plumbus",
        }
    ]
}
```

## Disable Convert Underscores { #disable-convert-underscores }

The same way as with regular header parameters, when you have underscore characters in the parameter names, they are **automatically converted to hyphens**.

For example, if you have a header parameter `save_data` in the code, the expected HTTP header will be `save-data`, and it will show up like that in the docs.

## Advanced description from docstring { #advanced-description-from-docstring }

You can limit the lines used from the docstring of a *path operation function* for OpenAPI.

Adding an `\f` (an escaped "form feed" character) causes **FastAPI** to truncate the output used for OpenAPI at this point.

It won't show up in the documentation, but other tools (such as Sphinx) will be able to use the rest.

* `write(data)`: Writes `data` (`str` or `bytes`) to the file.
* `read(size)`: Reads `size` (`int`) bytes/characters of the file.
* `seek(offset)`: Goes to the byte position `offset` (`int`) in the file.
    * E.g., `await myfile.seek(0)` would go to the start of the file.

{* ../../docs_src/query_params/tutorial001.py hl[9] *}

La query es el conjunto de pares clave-valor que van después del `?` en una URL, separados por caracteres `&`.

Por ejemplo, en la URL:

```
http://127.0.0.1:8000/items/?skip=0&limit=10
```

...los parámetros de query son:

* `skip`: con un valor de `0`
* `limit`: con un valor de `10`

    }

    @Test
    @DisplayName("Should handle notification with Unicode characters")
    void testUnicodeFilenames() throws Exception {
        // Given
        byte[] buffer = new byte[512];
        int offset = 0;

        setHeaderStart(response, 64);

        String unicodeName = "文件名.txt"; // Chinese characters
        byte[] fileNameBytes = unicodeName.getBytes("UnicodeLittleUnmarked");