private static Optional<String> lookupMessage(int code) {
        int[] codes = WinError.WINERR_CODES;
        String[] msgs = WinError.WINERR_MESSAGES;
        for (int i = 0; i < codes.length; i++) {
            if (codes[i] == code) {
                return Optional.of(msgs[i]);
            }
        }
        return Optional.empty();
    }

from typing import Optional


def say_hi(name: Optional[str] = None):
    if name is not None:
        print(f"Hey {name}!")
    else:

from typing import Optional

from fastapi import FastAPI, File
from fastapi.testclient import TestClient

app = FastAPI()


@app.post("/files")
async def upload_files(files: Optional[list[bytes]] = File(None)):
    if files is None:
        return {"files_count": 0}
    return {"files_count": len(files), "sizes": [len(f) for f in files]}


def test_optional_bytes_list():
    client = TestClient(app)
    response = client.post(

 */
@Beta
public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> {
  boolean allowsParallelEdges = false;
  ElementOrder<? super E> edgeOrder = ElementOrder.insertion();
  Optional<Integer> expectedEdgeCount = Optional.absent();

  /** Creates a new instance with the specified edge directionality. */
  private NetworkBuilder(boolean directed) {
    super(directed);
  }

    }

    @Override
    public Language language() {
        return (language != null) ? language : SourceRoot.super.language();
    }

    @Override
    public Optional<String> module() {
        return Optional.ofNullable(moduleName);
    }

    @Override
    public PathMatcher matcher(Collection<String> defaultIncludes, boolean useDefaultExcludes) {
        return null; // Not used for this test.
    }

        this.prompter = prompter;
    }

    @Override
    public String description() {
        return "Secure console password prompt";
    }

    @Override
    public Optional<String> configTemplate() {
        return Optional.empty();
    }

    @Override
    public String handle(String config) throws SecDispatcherException {
        if (NAME.equals(config)) {
            try {

      </dependency>
      <dependency>
        <groupId>maven-test</groupId>
        <artifactId>t06-d</artifactId>
        <version>1.0</version>
        <scope>test</scope>
        <optional>false</optional>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>maven-test</groupId>
      <artifactId>t06-a</artifactId>
      <version>1.0</version>

이 응용 프로그램을 예로 들어보겠습니다:

{* ../../docs_src/query_params_str_validations/tutorial001.py hl[9] *}

쿼리 매개변수 `q`는 `Optional[str]` 자료형입니다. 즉, `str` 자료형이지만 `None` 역시 될 수 있음을 뜻하고, 실제로 기본값은 `None`이기 때문에 FastAPI는 이 매개변수가 필수가 아니라는 것을 압니다.

/// note | 참고

FastAPI는 `q`의 기본값이 `= None`이기 때문에 필수가 아님을 압니다.

`Optional[str]`에 있는 `Optional`은 FastAPI가 사용하는게 아니지만, 편집기에게 더 나은 지원과 오류 탐지를 제공하게 해줍니다.

///

## 추가 검증

        stablePublicInterface = instanceScopedPool.get(StablePublicInterface.name)

        apiClass.changeStatus >> JApiChangeStatus.MODIFIED
        apiClass.oldClass >> Optional.of(oldBase)
        apiClass.newClass >> Optional.of(newBase)

        internalInterface.name = replaceAsInternal(internalInterface.name)

        interfaces = ['internal': internalInterface,

  /** Puts all the associations from {@code rangeMap} into this range map (optional operation). */
  void putAll(RangeMap<K, ? extends V> rangeMap);

  /** Removes all associations from this range map (optional operation). */
  void clear();

  /**
   * Removes all associations from this range map in the specified range (optional operation).
   *