new API, `Call.isCanceled()` to check if a call has been canceled.

 *  New: Update `MultipartBuilder` to support content length.
 *  New: Make it possible to mock `OkHttpClient` and `Call`.
 *  New: Update to h2-14 and hpack-9.
 *  New: OkHttp includes a user-agent by default, like `okhttp/2.1.0-RC1`.
 *  Fix: Handle response code `308 Permanent Redirect`.

 * layer primitives: connections, requests, responses, and streams.
 *
 * This class supports [asynchronous canceling][cancel]. This is intended to have the smallest
 * blast radius possible. If an HTTP/2 stream is active, canceling will cancel that stream but not
 * the other streams sharing its connection. But if the TLS handshake is still in progress then
 * canceling may break the entire connection.
 */

`ujson` is less careful than Python's built-in implementation in how it handles some edge-cases.

///

```Python hl_lines="2  7"
{!../../docs_src/custom_response/tutorial001.py!}
```

/// tip

It's possible that `ORJSONResponse` might be a faster alternative.

///

### `RedirectResponse`

Returns an HTTP redirect. Uses a 307 status code (Temporary Redirect) by default.

   * source, and finally additional bytes are appended to the source before the stream is read.
   *
   * <p>Without special handling, it's possible to have reads of the open stream start <i>before</i>
   * the offset at which the slice is supposed to start.
   */
  // TODO(cgdecker): Maybe add a test for this to ByteSourceTester

   * suitable for testing that map entries cannot be modified via a nefarious implementation of
   * equals. This is used for testing unmodifiable collections of map entries; for example, it
   * should not be possible to access the raw (modifiable) map entry via a nefarious equals method.
   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      Entry<K, V> nefariousMapEntry(K key, V value) {

  }

  // Element Mutation

  @Test
  public void addEdge_existingNodes() {
    assume().that(graphIsMutable()).isTrue();

    // Adding nodes initially for safety (insulating from possible future
    // modifications to proxy methods)
    addNode(N1);
    addNode(N2);
    assertThat(networkAsMutableNetwork.addEdge(N1, N2, E12)).isTrue();
    assertThat(network.edges()).contains(E12);

  }

  // Element Mutation

  @Test
  public void addEdge_existingNodes() {
    assume().that(graphIsMutable()).isTrue();

    // Adding nodes initially for safety (insulating from possible future
    // modifications to proxy methods)
    addNode(N1);
    addNode(N2);
    assertThat(networkAsMutableNetwork.addEdge(N1, N2, E12)).isTrue();
    assertThat(network.edges()).contains(E12);

		panic("invalid format")
	}

	// Update checksum.
	// This field is special in that it is terminated by a NULL then space.
	var f formatter
	field := b.toV7().chksum()
	chksum, _ := b.computeChecksum() // Possible values are 256..128776
	f.formatOctal(field[:7], chksum) // Never fails since 128776 < 262143
	field[7] = ' '
}

// computeChecksum computes the checksum for the header block.

	// with the common name "foo" will be associated with the policy "foo".
	// Other mapping functions - e.g. public-key hash based mapping - are
	// possible but not implemented.
	//
	// Group mapping is not possible with standard X.509 certificates.
	if certificate.Subject.CommonName == "" {
		writeSTSErrorResponse(ctx, w, ErrSTSMissingParameter, errors.New("certificate subject CN cannot be empty"))
		return

 *
 * <p><b>Important note:</b> Unlike {@code InetAddress.getByName()}, the methods of this class never
 * cause DNS services to be accessed. For this reason, you should prefer these methods as much as
 * possible over their JDK equivalents whenever you are expecting to handle only IP address string
 * literals -- there is no blocking DNS penalty for a malformed string.
 *