The same way, you can define logic (code) that should be executed when the application is **shutting down**. In this case, this code will be executed **once**, **after** having handled possibly **many requests**.

Because this code is executed before the application **starts** taking requests, and right after it **finishes** handling requests, it covers the whole application **lifespan** (the word "lifespan" will be important in a second 😉).

import okhttp3.internal.assertNotHeld
import okhttp3.internal.okHttpName

/**
 * A set of tasks that are executed in sequential order.
 *
 * Work within queues is not concurrent. This is equivalent to each queue having a dedicated thread
 * for its work; in practice a set of queues may share a set of threads to save resources.
 */
class TaskQueue internal constructor(
  internal val taskRunner: TaskRunner,
  internal val name: String,

```Python hl_lines="10"
{!> ../../docs_src/query_params_str_validations/tutorial002_an.py!}
```

////

Notice that the default value is still `None`, so the parameter is still optional.

But now, having `Query(max_length=50)` inside of `Annotated`, we are telling FastAPI that we want it to have **additional validation** for this value, we want it to have maximum 50 characters. 😎

/// tip

```

...this would work:

```JSON
{
    "item_id": "foo-item",
    "needy": "sooooneedy"
}
```

And of course, you can define some parameters as required, some as having a default value, and some entirely optional:

//// tab | Python 3.10+

```Python hl_lines="8"
{!> ../../docs_src/query_params/tutorial006_py310.py!}
```

////

//// tab | Python 3.8+

    @SuppressWarnings({
      "unused",
      /*
       * Since reflection can't tell the difference between <T> and <T extends Object>, it doesn't
       * make a ton of sense to have a separate tests for each. But having tests for each doesn't
       * really hurt anything, and maybe it will serve a purpose in a future in which Java has a
       * built-in nullness feature?
       */
      "ExtendsObject",
    })

    @SuppressWarnings({
      "unused",
      /*
       * Since reflection can't tell the difference between <T> and <T extends Object>, it doesn't
       * make a ton of sense to have a separate tests for each. But having tests for each doesn't
       * really hurt anything, and maybe it will serve a purpose in a future in which Java has a
       * built-in nullness feature?
       */
      "ExtendsObject",
    })

      and apparatus claims, in any patent Licensable by such Contributor that
      would be infringed, but for the grant of the License, by the making,
      using, selling, offering for sale, having made, import, or transfer of
      either its Contributions or its Contributor Version.

1.12. “Secondary License”

      means either the GNU General Public License, Version 2.0, the GNU Lesser

## Conflict Resolution

Conflicts in an open source project can take many forms, from someone having a bad day and using harsh and hurtful language in the issue queue, to more serious instances such as sexist/racist statements or threats of violence, and everything in between.

   */
  open fun requestHeadersEnd(
    call: Call,
    request: Request,
  ) {
  }

  /**
   * Invoked just prior to sending a request body.  Will only be invoked for request allowing and
   * having a request body to send.
   *
   * The connection is implicit, and will generally relate to the last [connectionAcquired] event.
   *

   * this initiates service shutdown and returns immediately. If the service is {@linkplain
   * State#NEW new}, it is {@linkplain State#TERMINATED terminated} without having been started nor
   * stopped. If the service has already been stopped, this method returns immediately without
   * taking action.
   *
   * @return this
   * @since 15.0
   */
  @CanIgnoreReturnValue
  Service stopAsync();

  /**