starting in Go 1.21, a main package's source files
can include one or more `//go:debug` directives at the top of the file
(preceding the `package` statement).
The `godebug` lines in the previous example would be written:

	//go:debug default=go1.21
	//go:debug panicnil=1
	//go:debug asynctimerchan=0

Starting in Go 1.21, the Go toolchain treats a `//go:debug` directive

		if cr.debug {
			fmt.Printf("prefix, want prefix %q, got %q", "x-amz-trailer-signature:", string(sig))
		}
		return errMalformedEncoding
	}

	// TODO: It seems like we may have to be prepared to rewrite and sort trailing headers:
	// https://docs.aws.amazon.com/IAM/latest/UserGuide/create-signed-request.html

	// Any value must end with a newline.
	// Not all clients send that.
	trailerRaw := valueBuffer.Bytes()

			return nil
		}
		// Don't wait for result
		return nil
	}

	// respCh must be set to wait for result.
	// We make it size 1, so a result can always be written
	// even if we aren't listening.
	task.respCh = make(chan healResult, 1)
	select {
	case globalBackgroundHealRoutine.tasks <- task:
		if serverDebugLog {
			fmt.Printf("Task in the queue: %#v\n", task)
		}

次の章では、FastAPIアプリケーションをデプロイするための**具体的なレシピ**を紹介します。

しかし、今はこれらの重要な**コンセプトに基づくアイデア**を確認しましょう。これらのコンセプトは、他のどのタイプのWeb APIにも当てはまります。💡

## セキュリティ - HTTPS

<!-- NOTE: https.md written in Japanese does not exist, so it redirects to English one  -->
[前チャプターのHTTPSについて](https.md){.internal-link target=_blank}では、HTTPSがどのようにAPIを暗号化するのかについて学びました。

submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose...

 *  Fix: Don't start the clock on response timeouts until the request body is fully transmitted.
    This is only relevant for duplex request bodies, because they are written concurrently when
    reading the response body.

 *  New: `MockResponse.inTunnel()` is a new `mockwebserver3` API to configure responses that are

   *
   * @param buffer A {@link ByteBuffer} with at least BYTES {@link ByteBuffer#remaining}, ordered as
   *     {@link ByteOrder#LITTLE_ENDIAN}, to which a BYTES-long byte representation of this instance
   *     is written. In the process increases the position of {@link ByteBuffer} by BYTES.
   */
  void writeTo(ByteBuffer buffer) {
    checkNotNull(buffer);
    checkArgument(
        buffer.remaining() >= BYTES,

   * set a value to {@code null} will result in a {@link NullPointerException}.
   *
   * <p>The returned list maintains the values, but not the identities, of {@code Character} objects
   * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
   * the returned list is unspecified.
   *
   * <p>The returned list is serializable.
   *

	for i, eVer := range eVers.versions {
		oVer := oVers.versions[i]
		if eVer.header != oVer.header {
			if eVer.header.hasEC() != oVer.header.hasEC() {
				// One version has EC and the other doesn't - may have been written later.
				// Compare without considering EC.
				a, b := eVer.header, oVer.header
				a.EcN, a.EcM = 0, 0
				b.EcN, b.EcM = 0, 0
				if a == b {
					continue
				}
			}

		Description:    "Invalid UTF-8 character detected.",
		HTTPStatusCode: http.StatusBadRequest,
	},
}

// toAPIErrorCode - Converts embedded errors. Convenience
// function written to handle all cases where we have known types of
// errors returned by underlying layers.
func toAPIErrorCode(ctx context.Context, err error) (apiErr APIErrorCode) {
	if err == nil {
		return ErrNone
	}