}

  private <T> void assertNextPermutation(
      List<T> expectedPermutation, Iterator<List<T>> permutations) {
    assertTrue("Expected another permutation, but there was none.", permutations.hasNext());
    assertEquals(expectedPermutation, permutations.next());
  }

  private <T> void assertNoMorePermutations(Iterator<List<T>> permutations) {

이는 **FastAPI**의 한계가 아니라, HTTP 프로토콜에 의한 것입니다.

///

## 선택적 파일 업로드 { #optional-file-upload }

표준 타입 애너테이션을 사용하고 기본값을 `None`으로 설정하여 파일을 선택적으로 만들 수 있습니다:

{* ../../docs_src/request_files/tutorial001_02_an_py310.py hl[9,17] *}

## 추가 메타데이터를 포함한 `UploadFile` { #uploadfile-with-additional-metadata }

	newSignature := getSignature(signingKey, stringToSign)

	// Verify if signature match.
	if !compareSignatureV4(newSignature, signV4Values.Signature) {
		return ErrSignatureDoesNotMatch
	}

	// Return error none.
	return ErrNone

```Python
from typing import Union
from fastapi import Cookie, FastAPI, Header, Path, Query

app = FastAPI()


@app.get("/items/{item_id}")
def main(
    item_id: int = Path(gt=0),
    query: Union[str, None] = Query(default=None, max_length=10),
    session: Union[str, None] = Cookie(default=None, min_length=3),

          .put(OptionalDouble.class, OptionalDouble.empty())
          .put(UUID.class, UUID.randomUUID())
          // common.base
          .put(CharMatcher.class, CharMatcher.none())
          .put(Joiner.class, Joiner.on(','))
          .put(Splitter.class, Splitter.on(','))
          .put(com.google.common.base.Optional.class, com.google.common.base.Optional.absent())

import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | 豆知識

[`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) の第2引数は、返されるデフォルト値です。

指定しない場合、デフォルトは`None`ですが、ここでは使用するデフォルト値として`"World"`を指定しています。

///

次に、このPythonプログラムを呼び出します。

//// tab | Linux, macOS, Windows Bash

<div class="termy">

```console
// ここではまだ環境変数を設定していません
$ python main.py

	}
	ch := make(chan Response, 1)
	m.respMu.Lock()
	if m.closed {
		m.respMu.Unlock()
		return nil, ErrDisconnected
	}
	m.respWait = ch
	m.respMu.Unlock()
	ctx := m.ctx

	// Add deadline if none.
	if msg.DeadlineMS == 0 {
		msg.DeadlineMS = uint32(defaultSingleRequestTimeout / time.Millisecond)
		var cancel context.CancelFunc
		ctx, cancel = context.WithTimeout(ctx, defaultSingleRequestTimeout)
		defer cancel()

                                        <la:select styleId="ssoType" property="ssoType" styleClass="form-control">
                                            <la:option value="none">None</la:option>
                                            <la:option value="oic">OpenID Connect</la:option>
                                            <la:option value="saml">SAML</la:option>

```Python
from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str | None = None):
    return {"item_id": item_id, "q": q}
```

### Dockerfile { #dockerfile }

现在在同一个项目目录下创建 `Dockerfile` 文件：

```{ .dockerfile .annotate }
# (1)!
FROM python:3.14

# (2)!

    /** Constant representing automatic mode. */
    public static final String AUTO = "auto";

    /** Constant representing no value or empty state. */
    public static final String NONE = "none";

    // ============================================================
    // Item/Field Identifiers
    // ============================================================