* **Convertir datos**: de la request al tipo requerido.
* **Validar datos**: provenientes de cada request:
    * Generando **errores automáticos** devueltos al cliente cuando los datos son inválidos.
* **Documentar** la API usando OpenAPI:
    * Que luego es usada por las interfaces de documentación interactiva automática.

* **تبدیل داده**: از درخواست به نوع مورد نیاز.
* **اعتبارسنجی داده**: که از هر درخواست میاد:
    * تولید **خطاهای خودکار** که به کلاینت برمی‌گرده وقتی داده نامعتبره.
* **مستندسازی** API با استفاده از OpenAPI:
    * که بعدش توسط رابط‌های کاربری مستندات تعاملی خودکار استفاده می‌شه.

     * it returns a subclass of Joiner that overrides this method to tolerate null inputs.
     *
     * Unfortunately, we don't distinguish between these two cases in our public API: Joiner.on(...)
     * and Joiner.on(...).useForNull(...) both declare the same return type: plain Joiner. To ensure
     * that users *can* pass null arguments to Joiner, we annotate it as if it always tolerates null

この場合、`int`のキーと`float`の値を持つものであれば、どんな`dict`でも受け入れることができます:

{* ../../docs_src/body_nested_models/tutorial009.py hl[15] *}

/// tip | 豆知識

JSONはキーとして`str`しかサポートしていないことに注意してください。

しかしPydanticには自動データ変換機能があります。

これは、APIクライアントがキーとして文字列しか送信できなくても、それらの文字列に純粋な整数が含まれている限り、Pydanticが変換して検証することを意味します。

そして、`weights`として受け取る`dict`は、実際には`int`のキーと`float`の値を持つことになります。

///

## まとめ

 * the same single element. The total number of occurrences of an element in a multiset is called
 * the <i>count</i> of that element (the terms "frequency" and "multiplicity" are equivalent, but
 * not used in this API). Since the count of an element is represented as an {@code int}, a multiset
 * may never contain more than {@link Integer#MAX_VALUE} occurrences of any one element.
 *

 *       However, utilities that <i>use</i> that executor have the ability to interrupt tasks
 *       running on it. This class, by contrast, does not expose an {@code Executor} API.)
 * </ul>
 *
 * <p>If you don't need the features of this class, you may prefer {@code newSequentialExecutor} for
 * its simplicity and ability to accommodate interruption.
 *
 * @since 26.0
 */
@J2ktIncompatible

* **Converter dados**: da solicitação para o tipo necessário.
* **Validar dados**: provenientes de cada solicitação:
    * Gerando **erros automáticos** retornados ao cliente quando os dados são inválidos.
* **Documentar** a API usando OpenAPI:
    * que é usado pelas interfaces de usuário da documentação interativa automática.

    pongQueue.add(payload)
    runWriter()
    receivedPingCount++
  }

  @Synchronized override fun onReadPong(payload: ByteString) {
    // This API doesn't expose pings.
    receivedPongCount++
    awaitingPong = false
  }

  override fun onReadClose(
    code: Int,
    reason: String,
  ) {
    require(code != -1)

   * in the subdomain list. The number of levels must be non-negative, and less than {@code N-1},
   * where {@code N} is the number of parts in the domain.
   *
   * <p>TODO: Reasonable candidate for addition to public API.
   */
  private InternetDomainName ancestor(int levels) {
    ImmutableList<String> ancestorParts = parts.subList(levels, parts.size());

			return true
		}
		if errors.Is(nerr.Err, rest.ErrClientClosed) {
			return true
		}
	}
	if errors.Is(err, grid.ErrDisconnected) {
		return true
	}
	// More corner cases suitable for storage REST API
	switch {
	// A peer node can be in shut down phase and proactively
	// return 503 server closed error, consider it as an offline node
	case strings.Contains(err.Error(), http.ErrServerClosed.Error()):
		return true