public static final String KEEP_ALIVE = "Keep-Alive";

  /**
   * The HTTP <a href="https://github.com/WICG/nav-speculation/blob/main/no-vary-search.md">{@code
   * No-Vary-Seearch}</a> header field name.
   *
   * @since 32.0.0
   */
  public static final String NO_VARY_SEARCH = "No-Vary-Search";

  /**
   * The HTTP <a href="https://googlechrome.github.io/OriginTrials/#header">{@code Origin-Trial}</a>
   * header field name.

 *
 * Install OpenSC separately. On a mac `brew cast install opensc`.
 */
@SuppressSignatureCheck
class YubikeyClientAuth {
  fun run() {
    // The typical PKCS11 slot, may vary with different hardware.
    val slot = 0

    val config = "--name=OpenSC\nlibrary=/Library/OpenSC/lib/opensc-pkcs11.so\nslot=$slot\n"

    // May fail with ProviderException with root cause like

          println("Server: ${response.header("Server")}")
          println("Date: ${response.header("Date")}")
          println("Vary: ${response.headers("Vary")}")
        }
      }
    ```

=== ":material-language-java: Java"
    ```java
      private final OkHttpClient client = new OkHttpClient();

      public void run() throws Exception {

  @Nullable V forcePut(@ParametricNullness K key, @ParametricNullness V value);

  // Bulk Operations

  /**
   * {@inheritDoc}
   *
   * <p><b>Warning:</b> the results of calling this method may vary depending on the iteration order
   * of {@code map}.
   *
   * @throws IllegalArgumentException if an attempt to {@code put} any entry fails. Note that some

    @Test
    void testToStringWithOptions() throws DcerpcException {
        dcerpcBinding.setOption("connect", "80");
        dcerpcBinding.setOption("bind", "123");
        // Order of options in toString might vary due to HashMap, so check for containment
        String result = dcerpcBinding.toString();
        assertTrue(result.startsWith(PROTO + ":" + SERVER + "[null,"), "toString should start correctly.");

  resolved "https://registry.yarnpkg.com/utils-merge/-/utils-merge-1.0.1.tgz#9f95710f50a267947b2ccc124741c1028427e713"
  integrity sha1-n5VxD1CiZ5R7LMwSR0HBAoQn5xM=

vary@^1:
  version "1.1.2"
  resolved "https://registry.yarnpkg.com/vary/-/vary-1.1.2.tgz#2299f02c6ded30d4a5961b0b9f74524a18f634fc"
  integrity sha1-IpnwLG3tMNSllhsLn3RSShj2NPw=

void-elements@^2.0.0:
  version "2.0.1"

  @Nullable V forcePut(@ParametricNullness K key, @ParametricNullness V value);

  // Bulk Operations

  /**
   * {@inheritDoc}
   *
   * <p><b>Warning:</b> the results of calling this method may vary depending on the iteration order
   * of {@code map}.
   *
   * @throws IllegalArgumentException if an attempt to {@code put} any entry fails. Note that some

## Documenting the callback { #documenting-the-callback }

The actual callback code will depend heavily on your own API app.

And it will probably vary a lot from one app to the next.

It could be just one or two lines of code, like:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"

    cacheHit
      .cacheResponse()
      .assertCode(200)
      .assertHeader("Donut", "a")
      .assertHeader("ETag", "v1")
      .assertRequestUrl(server.url("/"))
      .assertRequestHeader("Accept-Language") // No Vary on Accept-Language.
      .assertRequestHeader("Accept-Charset", "UTF-8") // Because of Vary on Accept-Charset.

	{nil, []byte(""), 0},
	{[]byte("a"), nil, 1},
	{nil, []byte("a"), -1},
}

func TestCompare(t *testing.T) {
	for _, tt := range compareTests {
		numShifts := 16
		buffer := make([]byte, len(tt.b)+numShifts)
		// vary the input alignment of tt.b
		for offset := 0; offset <= numShifts; offset++ {
			shiftedB := buffer[offset : len(tt.b)+offset]
			copy(shiftedB, tt.b)
			cmp := Compare(tt.a, shiftedB)
			if cmp != tt.i {