## Using `BackgroundTasks` { #using-backgroundtasks }

First, import `BackgroundTasks` and define a parameter in your *path operation function* with a type declaration of `BackgroundTasks`:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[1,13] *}

**FastAPI** will create the object of type `BackgroundTasks` for you and pass it as that parameter.

## Create a task function { #create-a-task-function }

/// info | Info

`Form` ist eine Klasse, die direkt von `Body` erbt.

///

/// tip | Tipp

Um Formularbodys zu deklarieren, verwenden Sie explizit `Form`, da diese Parameter sonst als Query-Parameter oder Body (JSON)-Parameter interpretiert werden würden.

///

## Über „Formularfelder“ { #about-form-fields }

# Response-Header { #response-headers }

## Einen `Response`-Parameter verwenden { #use-a-response-parameter }

Sie können einen Parameter vom Typ `Response` in Ihrer *Pfadoperation-Funktion* deklarieren (wie Sie es auch für Cookies tun können).

Und dann können Sie Header in diesem *vorübergehenden* <abbr title="Response – Antwort: Daten, die der Server zum anfragenden Client zurücksendet">Response</abbr>-Objekt festlegen.

        default:
            return "Unknown error: 0x" + Integer.toHexString(returnCode);
        }
    }

    /**
     * Encodes the witness RPC message parameters to NDR format.
     * Subclasses must implement this method to encode their specific parameters.
     *
     * @param buf the NDR buffer to encode into
     * @throws NdrException if encoding fails
     */

    private final Map<String, Parameter> missingParameters;

    ValidatingConfigurationListener(Object mojo, MojoDescriptor mojoDescriptor, ConfigurationListener delegate) {
        this.mojo = mojo;
        this.delegate = delegate;
        this.missingParameters = new HashMap<>();

        if (mojoDescriptor.getParameters() != null) {
            for (Parameter param : mojoDescriptor.getParameters()) {

    /**
     * Constructs a new HostIntervalController with default parameters.
     */
    public HostIntervalController() {
        this.lastTimes = CacheBuilder.newBuilder().expireAfterAccess(DEFAULT_CACHE_EXPIRE_HOURS, TimeUnit.HOURS).build();
    }

    /**
     * Constructs a new HostIntervalController with the specified parameters.
     *
     * @param params the parameters to configure the interval controller
     */

 * without throwing exceptions.
 */
@ExtendWith(MockitoExtension.class)
class MsrpcSamrConnect2Test {

    // Helper method to create a minimal SamrPolicyHandle instance.
    private static SamrPolicyHandle createMockPolicyHandle() {
        return mock(SamrPolicyHandle.class);
    }

    @Nested
    @DisplayName("Constructor parameter handling")

        return now + days * Constants.ONE_DAY_IN_MILLIS;
    }

    /**
     * Retrieves all crawling information parameters for the specified session as a map.
     *
     * @param sessionId the session ID to retrieve parameters for
     * @return a map containing all key-value parameter pairs for the session
     */
    public Map<String, String> getInfoMap(final String sessionId) {

    }

    /**
     * Builds parameter maps for search initialization, creating both query strings
     * and form inputs for the given parameters.
     *
     * @param paramMap the parameter map to process
     * @param queryKey the key for storing query string parameters
     * @param formKey the key for storing form input parameters
     */

func (l *List[T]) Len() int  { … }
</pre>

<h3 id="Type_parameter_declarations">Type parameter declarations</h3>

<p>
A type parameter list declares the <i>type parameters</i> of a generic function or type declaration.
The type parameter list looks like an ordinary <a href="#Function_types">function parameter list</a>
except that the type parameter names must all be present and the list is enclosed
in square brackets rather than parentheses