And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

/// info

Keep in mind that dataclasses can't do everything Pydantic models can do.

@GwtCompatible
public abstract class DiscreteDomain<C extends Comparable> {

  /**
   * Returns the discrete domain for values of type {@code Integer}.
   *
   * <p>This method always returns the same object. That object is serializable; deserializing it
   * results in the same object too.
   *
   * @since 14.0 (since 10.0 as {@code DiscreteDomains.integers()})
   */
  public static DiscreteDomain<Integer> integers() {
    return IntegerDomain.INSTANCE;

        ProtwordsItem item4 = new ProtwordsItem(1, "word");

        // Same object
        assertTrue(item1.equals(item1));

        // Same input, different id
        assertTrue(item1.equals(item2));

        // Different input
        assertFalse(item1.equals(item3));

        // Same id and input
        assertTrue(item1.equals(item4));

        // Null object

So:

```Python
q: str | None = Query(default=None)
```

...makes the parameter optional, with a default value of `None`, the same as:


```Python
q: str | None = None
```

@GwtCompatible
public abstract class DiscreteDomain<C extends Comparable> {

  /**
   * Returns the discrete domain for values of type {@code Integer}.
   *
   * <p>This method always returns the same object. That object is serializable; deserializing it
   * results in the same object too.
   *
   * @since 14.0 (since 10.0 as {@code DiscreteDomains.integers()})
   */
  public static DiscreteDomain<Integer> integers() {
    return IntegerDomain.INSTANCE;

If you pass a "callable" as a dependency in **FastAPI**, it will analyze the parameters for that "callable", and process them in the same way as the parameters for a *path operation function*. Including sub-dependencies.

That also applies to callables with no parameters at all. The same as it would be for *path operation functions* with no parameters.

        when(mockChannelManager.getHealthyChannels()).thenReturn(Arrays.asList(channel1, channel2));

        // Multiple calls with same file ID should return same channel
        ChannelInfo first = loadBalancer.selectChannel(readRequest);
        ChannelInfo second = loadBalancer.selectChannel(readRequest);

        assertEquals(first, second);
    }

**FastAPI** knows what to do in each case and how to reuse the same object, so that all the background tasks are merged together and are run in the background afterwards:


{* ../../docs_src/background_tasks/tutorial002_an_py310.py hl[13,15,22,25] *}

import junit.framework.TestCase;

/**
 * Test cases for {@code EventBus} that must not be in the same package.
 *
 * @author Louis Wasserman
 */
public class OutsideEventBusTest extends TestCase {

  /*
   * If you do this test from common.eventbus.EventBusTest, it doesn't actually test the behavior.
   * That is, even if exactly the same method works from inside the common.eventbus package tests,
   * it can fail here.
   */

 *     their equivalent on the result of {@code Traverser.forTree(tree)} where {@code tree}
 *     implements {@code SuccessorsFunction}, which has a similar API as {@link #children} or can be
 *     the same lambda function as passed into {@link #using(Function)}.
 *     <p>This class is scheduled to be removed in October 2019.
 */
// TODO(b/68134636): Remove by 2019-10
@Deprecated
@Beta
@GwtCompatible