* 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.
   *

And then you can return any object you need, as you normally would (a `dict`, a database model, etc).

And if you declared a `response_model`, it will still be used to filter and convert the object you returned.

**FastAPI** will use that *temporal* response to extract the cookies (also headers and status code), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

```

////

Those parameters are what **FastAPI** will use to "solve" the dependency.

In both cases, it will have:

* An optional `q` query parameter that is a `str`.
* A `skip` query parameter that is an `int`, with a default of `0`.
* A `limit` query parameter that is an `int`, with a default of `100`.

In both cases the data will be converted, validated, documented on the OpenAPI schema, etc.

## Use it

```Python hl_lines="5-7  13-18  24"
{!../../docs_src/handling_errors/tutorial003.py!}
```

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..."}
```

    By having the type as `int | None`, SQLModel will know that this column should be an `INTEGER` in the SQL database and that it should be `NULLABLE`.

* `Field(index=True)` tells SQLModel that it should create a **SQL index** for this column, that would allow faster lookups in the database when reading data filtered by this column.

 * acquire(1000)} will result in exactly the same throttling, if any), but it affects the throttling
 * of the <i>next</i> request. I.e., if an expensive task arrives at an idle RateLimiter, it will be
 * granted immediately, but it is the <i>next</i> request that will experience extra throttling,
 * thus paying for the cost of the expensive task.
 *

/// 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.

```

////

//// tab | Python 3.8+

```Python hl_lines="3  17"
{!> ../../docs_src/path_operation_configuration/tutorial001.py!}
```

////

That status code will be used in the response and will be added to the OpenAPI schema.

/// note | "Technical Details"

You could also use `from starlette import status`.

  // Requests with the dryRun attribute will be auto-rejected if they match a webhook with
  // sideEffects == Unknown or Some.
  optional string sideEffects = 6;

  // TimeoutSeconds specifies the timeout for this webhook. After the timeout passes,
  // the webhook call will be ignored or the API call will fail based on the
  // failure policy.

 * is {@link org.apache.maven.api.Node Node} and {@code pathScope == ""},
 * then the dependencies will be <i>collected</i>.
 * If the type is {@link org.apache.maven.api.Node Node} or
 * {@code List<}{@link org.apache.maven.api.Node Node}{@code >},
 * and {@code pathScope != ""}, the dependencies will be <i>flattened</i>.
 * Else the dependencies will be <i>resolved</i> and {@code pathScope} must be non empty,