{!../../docs_src/query_params_str_validations/tutorial002.py!}
```

Note que substituímos o valor padrão de `None` para `Query(default=None)`, o primeiro parâmetro de `Query` serve para o mesmo propósito: definir o valor padrão do parâmetro.

Então:

```Python
q: Union[str, None] = Query(default=None)
```

...Torna o parâmetro opcional, da mesma maneira que:

```Python
q: Union[str, None] = None
```

   * constant does not exist, {@link Optional#absent} is returned. A common use case is for parsing
   * user input or falling back to a default enum constant. For example, {@code
   * Enums.getIfPresent(Country.class, countryInput).or(Country.DEFAULT);}
   *
   * @since 12.0
   */
  public static <T extends Enum<T>> Optional<T> getIfPresent(Class<T> enumClass, String value) {
    checkNotNull(enumClass);

  <name>Paramdoc</name>
  <description><![CDATA[Documentation on parameter expressions supported by Maven for use in plugins.]]></description>
  <defaults>
    <default>
      <key>package</key>
      <value>org.apache.maven.usability.plugin</value>
    </default>
  </defaults>
  <classes>
    <class rootElement="true" xml.tagName="paramdoc">
      <version>1.0.0</version>
      <name>ExpressionDocumentation</name>

  // Depending on whether this is a V2 ckpt, initializes "reader_" or
  // "v2_reader_".
  std::vector<string> v2_path;
  if (Env::Default()->GetMatchingPaths(MetaFilename(filename), &v2_path).ok() &&
      !v2_path.empty()) {
    v2_reader_.reset(
        new BundleReader(Env::Default(), filename /* prefix to a V2 ckpt */));
    if (!v2_reader_->status().ok()) {
      tsl::Set_TF_Status_from_Status(status, v2_reader_->status());

      - "9000:9000"
      - "9001:9001"
    depends_on:
      - minio1
      - minio2
      - minio3
      - minio4
      - minio5
      - minio6
      - minio7
      - minio8

## By default this config uses default local driver,
## For custom volumes replace with volume driver configuration.
volumes:
  pdata1-1:
  pdata1-2:
  pdata2-1:
  pdata2-2:
  pdata3-1:
  pdata3-2:
  pdata4-1:
  pdata4-2:

				err = msgp.WrapError(err, "Time")
				return
			}
		case "Token":
			z.Token, err = dc.ReadString()
			if err != nil {
				err = msgp.WrapError(err, "Token")
				return
			}
		default:
			err = dc.Skip()
			if err != nil {
				err = msgp.WrapError(err)
				return
			}
		}
	}
	return
}

// EncodeMsg implements msgp.Encodable

 *   <li>notification of evicted (or otherwise removed) entries
 *   <li>accumulation of cache access statistics
 * </ul>
 *
 * <p>These features are all optional; caches can be created using all or none of them. By default,
 * cache instances created by {@code CacheBuilder} will not perform any type of eviction.
 *
 * <p>Usage example:
 *
 * <pre>{@code
 * LoadingCache<Key, Graph> graphs = CacheBuilder.newBuilder()

	}
	if wg.Spec.Template == nil {
		wg.Spec.Template = &networkingv1alpha3.WorkloadEntry{}
	}
	// default service account for an empty field is "default"
	if wg.Spec.Template.ServiceAccount == "" {
		wg.Spec.Template.ServiceAccount = "default"
	}
	return nil
}

// Creates all the relevant config for the given workload group and cluster

 * returned.
 *
 * <p>All default instances returned by {@link #get} are generics-safe. Clients won't get type
 * errors for using {@code get(Comparator.class)} as a {@code Comparator<Foo>}, for example.
 * Immutable empty instances are returned for collection types; {@code ""} for string; {@code 0} for
 * number types; reasonable default instance for other stateless types. For mutable types, a fresh

                    "type": "object",
                    "properties": {
                        "description": {"title": "Description", "type": "string"},
                        "type": {"title": "Type", "type": "string", "default": "plane"},
                        "size": {"title": "Size", "type": "integer"},
                    },
                },
                "CarItem": {
                    "title": "CarItem",