/// tip

All this might not seem as useful with these simple examples.

But you will see how useful it is in the chapters about **security**.

And you will also see the amounts of code it will save you.

You can write <a href="https://en.wikipedia.org/wiki/Markdown" class="external-link" target="_blank">Markdown</a> in the docstring, it will be interpreted and displayed correctly (taking into account docstring indentation).

{* ../../docs_src/path_operation_configuration/tutorial004_py310.py hl[17:25] *}

It will be used in the interactive docs:

{* ../../docs_src/dependencies/tutorial008c_an_py39.py hl[15:16] *}

In this case, the client will see an *HTTP 500 Internal Server Error* response as it should, given that we are not raising an `HTTPException` or similar, but the server will **not have any logs** or any other indication of what was the error. 😱

     * mirror, its URL and ID will be updated to match the values from the mirror specification. Repositories without a
     * matching mirror will pass through unchanged. Note: This method must be called before
     * {@link #injectAuthentication(List, List)} or the repositories will end up with the wrong credentials.
     *

 * that {@linkplain #mightContain(Object)} will erroneously return {@code true} for an object that
 * has not actually been put in the {@code BloomFilter}.
 *
 * <p>Bloom filters are serializable. They also support a more compact serial representation via the
 * {@link #writeTo} and {@link #readFrom} methods. Both serialized forms will continue to be

///

The files will be uploaded as "form data".

If you declare the type of your *path operation function* parameter as `bytes`, **FastAPI** will read the file for you and you will receive the contents as `bytes`.

Keep in mind that this means that the whole contents will be stored in memory. This will work well for small files.

{* ../../docs_src/handling_errors/tutorial003.py hl[5:7,13:18,24] *}

Here, if you request `/unicorns/yolo`, the *path operation* will `raise` a `UnicornException`.

But it will be handled by the `unicorn_exception_handler`.

So, you will receive a clean error, with an HTTP status code of `418` and a JSON content of:

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

   * one of the listener's callbacks will execute at once. However, multiple listeners' callbacks
   * may execute concurrently, and listeners may execute in an order different from the one in which
   * they were registered.
   *
   * <p>RuntimeExceptions thrown by a listener will be caught and logged. Any exception thrown
   * during {@code Executor.execute} (e.g., a {@code RejectedExecutionException}) will be caught and
   * logged.
   *

   * the source will contain the concatenated data from the streams of the underlying sources.
   *
   * <p>Only one underlying stream will be open at a time. Closing the concatenated stream will
   * close the open underlying stream.
   *
   * <p>Note: The input {@code Iterator} will be copied to an {@code ImmutableList} when this method

   * captured by the returned {@link ClosingFuture}).
   *
   * <p>If this {@code ClosingFuture} succeeds, the derived one will be equivalent to the one
   * returned by the function.
   *
   * <p>If this {@code ClosingFuture} fails, the function will not be called, and the derived {@code
   * ClosingFuture} will be equivalent to this one.
   *
   * <p>If the function throws an exception, that exception is used as the result of the derived