```

////

#### Using `Union` or `Optional` { #using-union-or-optional }

If you are using a Python version below 3.10, here's a tip from my very **subjective** point of view:

* 🚨 Avoid using `Optional[SomeType]`
* Instead ✨ **use `Union[SomeType, None]`** ✨.

    public <T> T lookup(Class<T> type, String name) {
        return null;
    }

    @Override
    public <T> Optional<T> lookupOptional(Class<T> type) {
        return Optional.empty();
    }

    @Override
    public <T> Optional<T> lookupOptional(Class<T> type, String name) {
        return Optional.empty();
    }

    @Override
    public <T> List<T> lookupList(Class<T> type) {
        return List.of();
    }

* `skip=20`: because you set it in the URL
* `limit=10`: because that was the default value

## Optional parameters { #optional-parameters }

The same way, you can declare optional query parameters, by setting their default to `None`:

{* ../../docs_src/query_params/tutorial002_py310.py hl[7] *}

In this case, the function parameter `q` will be optional, and will be `None` by default.

/// check

     *
     * @return the current project or {@code empty()} if not applicable
     */
    @Nonnull
    Optional<Project> getProject();

    /**
     * Gets the current mojo execution (if any).
     *
     * @return the current mojo execution or {@code empty()} if not applicable
     */
    @Nonnull
    Optional<MojoExecution> getMojoExecution();

    /**
     * Gets the exception that caused the event (if any).
     *

import java.util.Arrays;
import java.util.Optional;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

/**
 * Tests for {@link DosError}.  Since {@link DosError} only contains
 * constants, the tests exercise the data and small helper logic in this
 * test class.
 */
public class DosErrorTest {
    private static Optional<Integer> findNtStatus(int dosErrorCode) {

    "com.oracle.svm.core.annotate;resolution:=optional," +
    "com.oracle.svm.core.configure;resolution:=optional," +
    "dalvik.system;resolution:=optional," +
    "org.conscrypt;resolution:=optional," +
    "org.bouncycastle.*;resolution:=optional," +
    "org.openjsse.*;resolution:=optional," +
    "org.graalvm.nativeimage;resolution:=optional," +
    "org.graalvm.nativeimage.hosted;resolution:=optional," +

            }

            @Nonnull
            @Override
            public Optional<Path> getPath() {
                return Optional.ofNullable(path);
            }

            @Nonnull
            @Override
            public Optional<Source> getSource() {
                return Optional.ofNullable(source);
            }

            @Override

    assertEquals(
        com.google.common.base.Optional.absent(),
        generator.generateFresh(new TypeToken<com.google.common.base.Optional<String>>() {}));
    assertEquals(
        com.google.common.base.Optional.of("2"),
        generator.generateFresh(new TypeToken<com.google.common.base.Optional<String>>() {}));
    // Test that the first generated instance for different cgcb.Optional<T> is always absent().

//
// An object storage system can implement one, multiple, or all functions.
//
//   - Optional (mandatory if <IAMSTS> is true): Set Endpoints for IAM and STS processing.
//
//   - Optional: Set server preferences for Backup & Replication parallel sessions, batch size of deletes, and block sizes (before
//     compression). This is an optional area; by default, there should be no <SystemRecommendations> section in the

     * The default value is empty.
     */
    default Optional<String> module() {
        return Optional.empty();
    }

    /**
     * {@return the version of the platform where the code will be executed}.
     * In a Java environment, this is the value of the {@code --release} compiler option.
     * The default value is empty.
     */
    default Optional<Version> targetVersion() {
        return Optional.empty();