*
   * @since 8.0
   */
  public static final byte ESC = 27;

  /**
   * File Separator: These four information separators may be used within data in optional fashion,
   * except that their hierarchical relationship shall be: FS is the most inclusive, then GS, then
   * RS, and US is least inclusive. (The content and length of a File, Group, Record, or Unit are
   * not specified.)

     * Required field with maximum length of 100 characters.
     */
    @Required
    @Size(max = 100)
    public String name;

    /**
     * The version of the plugin to delete.
     * Optional field with maximum length of 100 characters.
     */
    @Size(max = 100)
    public String version;

import com.google.common.annotations.GwtCompatible;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Set;

/**
 * Optional features of classes derived from {@code Set}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible

import java.util.Locale;

import org.codelibs.fess.opensearch.config.bsentity.BsCrawlingInfoParam;
import org.codelibs.fess.opensearch.config.exbhv.CrawlingInfoBhv;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.optional.OptionalEntity;

/**
 * @author ESFlute (using FreeGen)
 */
public class CrawlingInfoParam extends BsCrawlingInfoParam {

    private static final long serialVersionUID = 1L;

        return artifact.isSelectedVersionKnown();
    }

    /** {@inheritDoc} */
    @Override
    public void setOptional(boolean optional) {
        artifact.setOptional(optional);
    }

    /** {@inheritDoc} */
    @Override
    public int hashCode() {
        int result = 17;

        result = 37 * result + getGroupId().hashCode();

* 変数`prices`は`dict`であり:
    * この`dict`のキーは`str`型です。（つまり、各項目の名前）
    * この`dict`の値は`float`型です。（つまり、各項目の価格）

#### `Optional`

また、`Optional`を使用して、変数が`str`のような型を持つことを宣言することもできますが、それは「オプション」であり、`None`にすることもできます。

```Python hl_lines="1 4"
{!../../docs_src/python_types/tutorial009.py!}
```

ただの`str`の代わりに`Optional[str]`を使用することで、エディタは値が常に`str`であると仮定している場合に実際には`None`である可能性があるエラーを検出するのに役立ちます。

#### ジェネリック型

    void connectLogon(CIFSContext tf) throws SmbException;

    /**
     * Sends an SMB request and returns the response
     * @param <T> the response type
     * @param request the request to send
     * @param params optional request parameters
     * @return response message
     * @throws CIFSException if an error occurs sending the request
     */

{* ../../docs_src/query_params_str_validations/tutorial006c.py hl[9] *}

/// tip

Pydantic, ❔ ⚫️❔ 🏋️ 🌐 💽 🔬 &amp; 🛠️ FastAPI, ✔️ 🎁 🎭 🕐❔ 👆 ⚙️ `Optional` ⚖️ `Union[Something, None]` 🍵 🔢 💲, 👆 💪 ✍ 🌅 🔃 ⚫️ Pydantic 🩺 🔃 <a href="https://docs.pydantic.dev/latest/concepts/models/#required-optional-fields" class="external-link" target="_blank">✔ 📦 🏑</a>.

///

## 🔢 🔢 📇 / 💗 💲

///

/// note

**FastAPI** saura que `q` est optionnel grâce au `=None`.

Le `Optional` dans `Optional[str]` n'est pas utilisé par **FastAPI** (**FastAPI** n'en utilisera que la partie `str`), mais il servira tout de même à votre éditeur de texte pour détecter des erreurs dans votre code.

///

import org.codelibs.fess.exception.SsoMessageException;
import org.codelibs.fess.sso.SsoManager;
import org.codelibs.fess.sso.SsoResponseType;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.optional.OptionalThing;
import org.lastaflute.web.Execute;
import org.lastaflute.web.UrlChain;
import org.lastaflute.web.login.credential.LoginCredential;
import org.lastaflute.web.login.exception.LoginFailureException;