def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">
<summary>O usa <code>async def</code>...</summary>

Si tu código usa `async` / `await`, usa `async def`:

```Python hl_lines="7  12"
from fastapi import FastAPI
from typing import Union

app = FastAPI()


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

	// the system's local character encoding happens to be.
	//
	// This flag should only be set if the user intends to encode a non-portable
	// ZIP file for a specific localized region. Otherwise, the Writer
	// automatically sets the ZIP format's UTF-8 flag for valid UTF-8 strings.
	NonUTF8 bool

	CreatorVersion uint16
	ReaderVersion  uint16
	Flags          uint16

def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">
<summary>Ya da <code>async def</code>...</summary>

Eğer kodunuzda `async` / `await` varsa, `async def` kullanalım:

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():

pkg log/slog, func New(Handler) *Logger #56345
pkg log/slog, func NewJSONHandler(io.Writer, *HandlerOptions) *JSONHandler #59339
pkg log/slog, func NewLogLogger(Handler, Level) *log.Logger #56345
pkg log/slog, func NewRecord(time.Time, Level, string, uintptr) Record #56345
pkg log/slog, func NewTextHandler(io.Writer, *HandlerOptions) *TextHandler #59339
pkg log/slog, func SetDefault(*Logger) #56345

It doesn't matter. **FastAPI** will know what to do.

/// note

If you don't know, check the [Async: *"In a hurry?"*](../../async.md#in-a-hurry){.internal-link target=_blank} section about `async` and `await` in the docs.

///

## Integrated with OpenAPI

All the request declarations, validations and requirements of your dependencies (and sub-dependencies) will be integrated in the same OpenAPI schema.

//
// The table's lower portion shows specialized features of each format,
// such as supported string encodings, support for sub-second timestamps,
// or support for sparse files.
//
// The Writer currently provides no support for sparse files.
type Format int

// Constants to identify various tar formats.
const (
	// Deliberately hide the meaning of constants from public API.

	if chainedCNIPlugin && delayedConfFile != "" {
		retry.UntilSuccessOrFail(t, func() error {
			if err := checkResult(resultFile, expectedOutputFile); err == nil {
				// We should have waited for the delayed conf
				return fmt.Errorf("did not wait for valid config file")
			}
			return nil
		}, retry.Delay(time.Millisecond), retry.Timeout(time.Millisecond*250))
		var destFilenm string

   * missRate =~ 1.0}. Cache misses include all requests which weren't cache hits, including
   * requests which resulted in either successful or failed loading attempts, and requests which
   * waited for other threads to finish loading. It is thus the case that {@code missCount >=
   * loadSuccessCount + loadExceptionCount}. Multiple concurrent misses for the same key will result
   * in a single load operation.
   */

   * missRate =~ 1.0}. Cache misses include all requests which weren't cache hits, including
   * requests which resulted in either successful or failed loading attempts, and requests which
   * waited for other threads to finish loading. It is thus the case that {@code missCount >=
   * loadSuccessCount + loadExceptionCount}. Multiple concurrent misses for the same key will result
   * in a single load operation.
   */

これにはクラウドストレージとの連携や映像処理など、多くのライブラリが含まれています。

```Python hl_lines="2  10-12  14"
{!../../docs_src/custom_response/tutorial008.py!}
```

/// tip | "豆知識"

ここでは `async` や `await` をサポートしていない標準の `open()` を使っているので、通常の `def` でpath operationを宣言していることに注意してください。

///

### `FileResponse`

レスポンスとしてファイルを非同期的にストリームします。

他のレスポンスタイプとは異なる引数のセットを受け取りインスタンス化します。