"INVISIBLE_MEMBER",
  "INVISIBLE_REFERENCE",
)

package okhttp3

import java.io.IOException
import okhttp3.internal.SuppressSignatureCheck

/** Data classes that correspond to each of the methods of [ConnectionListener]. */
@SuppressSignatureCheck
sealed class ConnectionEvent {
  abstract val timestampNs: Long
  open val connection: Connection?
    get() = null

### Instalar `pydantic-settings`

Primero, asegúrate de crear tu [entorno virtual](../virtual-environments.md){.internal-link target=_blank}, actívalo y luego instala el paquete `pydantic-settings`:

<div class="termy">

```console
$ pip install pydantic-settings
---> 100%
```

E `Field` do Pydantic retorna uma instância de `FieldInfo` também.

`Body` também retorna objetos de uma subclasse de `FieldInfo` diretamente. E tem outras que você verá mais tarde que são subclasses da classe `Body`.

* <a href="https://hub.docker.com/_/postgres" class="external-link" target="_blank">PostgreSQL</a>
* <a href="https://hub.docker.com/_/mysql" class="external-link" target="_blank">MySQL</a>
* <a href="https://hub.docker.com/_/mongo" class="external-link" target="_blank">MongoDB</a>
* <a href="https://hub.docker.com/_/redis" class="external-link" target="_blank">Redis</a>, usw.

En Python hay una forma de hacer que una instance de una clase sea un "callable".

No la clase en sí (que ya es un callable), sino una instance de esa clase.

Para hacer eso, declaramos un método `__call__`:

{* ../../docs_src/dependencies/tutorial011_an_py39.py hl[12] *}

import static org.junit.jupiter.api.Assertions.assertEquals;

/**
 * Verifies that subclasses from generated model classes are possible.
 */
class ExtendedPluginDescriptorTest {

    /**
     * A subclass of the generated class {@link PluginDescriptor} that adds an additional field.
     */
    static class ExtendedPluginDescriptor extends PluginDescriptor {

        private final String additionalField;

/**
 * This enforces us having the params classes on the classpath to workaround
 * https://github.com/graalvm/native-build-tools/issues/745
 */
class WithArgumentSourceTest {
  @ParameterizedTest
  @ArgumentsSource(FakeArgumentsProvider::class)
  fun passingTest(value: Int) {
    assertThat(value).isGreaterThan(0)
  }
}

internal class FakeArgumentsProvider : ArgumentsProvider {

     *       class path.</li>
     * </ul>
     */
    CLASSES(StandardLocation.CLASS_PATH, "--class-path"),

    /**
     * The path identified by the Java {@code --module-path} option.
     * Used for compilation, execution and Javadoc among others.
     * The Java tools location is {@link StandardLocation#MODULE_PATH}.
     *
     * <h4>Context-sensitive interpretation</h4>

## A "callable" instance { #a-callable-instance }

In Python there's a way to make an instance of a class a "callable".

Not the class itself (which is already a callable), but an instance of that class.

To do that, we declare a method `__call__`:

{* ../../docs_src/dependencies/tutorial011_an_py39.py hl[12] *}

você o importa e cria uma "instância" da mesma maneira que faria com a classe `FastAPI`:

```Python hl_lines="1  3" title="app/routers/users.py"
{!../../docs_src/bigger_applications/app/routers/users.py!}
```

### *Operações de Rota* com `APIRouter`

E então você o utiliza para declarar suas *operações de rota*.

Utilize-o da mesma maneira que utilizaria a classe  `FastAPI`:

```Python hl_lines="6  11  16" title="app/routers/users.py"