モダンな Python は **「非同期コード」** を **「コルーチン」** と呼ばれる仕組みでサポートしており、構文は **`async` と `await`** です。

以下のセクションで、このフレーズをパーツごとに見ていきます:

* **非同期コード**
* **`async` と `await`**
* **コルーチン**

## 非同期コード { #asynchronous-code }

非同期コードとは、言語 💬 がコードのどこかの時点で、コンピュータ/プログラム 🤖 に「どこか別のところで終わるまで、別の何か」を待つ必要があると伝える手段を持っている、ということです。その「別の何か」を「遅いファイル」📝 と呼ぶことにしましょう。

その間、コンピュータは「遅いファイル」📝 が終わるまで、他の作業を進められます。

  val directory: Path,
  private val appVersion: Int,
  internal val valueCount: Int,
  /** Returns the maximum number of bytes that this cache should use to store its data. */
  maxSize: Long,
  /** Used for asynchronous journal rebuilds. */
  taskRunner: TaskRunner,
) : Closeable,
  Flushable,
  Lockable {
  internal val fileSystem: FileSystem =
    object : ForwardingFileSystem(fileSystem) {
      override fun sink(

streaming                         (on|off)    set to 'on', to use streaming NATS server
streaming_async                   (on|off)    set to 'on', to enable asynchronous publish
streaming_max_pub_acks_in_flight  (number)    number of messages to publish without waiting for ACKs
streaming_cluster_id              (string)    unique ID for NATS streaming cluster

- Disabled the `SchedulerAsyncAPICalls` feature gate to mitigate a bug where its interaction with asynchronous preemption could degrade `kube-scheduler` performance, especially under high `kube-apiserver` load. ([#134400](https://github.com/kubernetes/kubernetes/pull/134400), [@macsko](https://github.com/macsko))

      this.routeDatabase = okHttpClient.routeDatabase
      this.taskRunner = okHttpClient.taskRunner
    }

    /**
     * Sets the dispatcher used to set policy and execute asynchronous requests. Must not be null.
     */
    fun dispatcher(dispatcher: Dispatcher) =
      apply {
        this.dispatcher = dispatcher
      }

    /**

 * article on <a href="https://github.com/google/guava/wiki/ListenableFutureExplained">{@code
 * ListenableFuture}</a>.
 *
 * <p>The main purpose of {@code ListenableFuture} is to help you chain together a graph of
 * asynchronous operations. You can chain them together manually with calls to methods like {@link
 * Futures#transform(ListenableFuture, Function, Executor) Futures.transform}, but you will often

    releases of OkHttp are not compatible with OkHttp 3.5. When upgrading to the new package
    please note that the `WebSocket` and `WebSocketCall` classes have been merged. Sending messages
    is now asynchronous and they may be enqueued before the web socket is connected.

 *  **OkHttp no longer attempts a direct connection if the system's HTTP proxy fails.** This

### DELETE operation in REST API

			err = x.setIdx(i, *ver)
		default:
			x.versions = append(x.versions[:i], x.versions[i+1:]...)
			// if uv has tiered content we add a
			// free-version to track it for
			// asynchronous deletion via scanner.
			if freeVersion, toFree := ver.ObjectV2.InitFreeVersion(fi); toFree {
				err = x.addVersion(freeVersion)
			}
		}

		if fi.Deleted {
			err = x.addVersion(ventry)
		}

	}

	// Empty fi.VersionID indicates that versioning is either
	// suspended or disabled on this bucket. RenameData will replace
	// the 'null' version. We add a free-version to track its tiered
	// content for asynchronous deletion.
	//
	// Note: RestoreObject and HealObject requests don't end up replacing the
	// null version and therefore don't require the free-version to track
	// anything