eventListener.requestFailed(call, e)
      trackFailure(e)
      throw e
    }
  }

  @Throws(IOException::class)
  fun createRequestBody(
    request: Request,
    duplex: Boolean,
  ): Sink {
    this.isDuplex = duplex
    val contentLength = request.body!!.contentLength()
    eventListener.requestBodyStart(call)
    val rawRequestBody = codec.createRequestBody(request, contentLength)

def process_items(items_t: tuple[int, int, str], items_s: set[bytes]):

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package mockwebserver3.internal.duplex

import java.io.IOException
import java.util.concurrent.CountDownLatch
import java.util.concurrent.FutureTask
import java.util.concurrent.LinkedBlockingQueue
import java.util.concurrent.TimeUnit

| ...header_n     | msgp bin array              | Header of last version
| ...metadata_n   | msgp bin array              | Metadata of last version

Each header contains a mspg array (tuple) encoded object:

xlHeaderVersion version == 1:

```
//msgp:tuple xlMetaV2VersionHeader
type xlMetaV2VersionHeader struct {
 VersionID [16]byte  // Version UUID, raw.
 ModTime   int64     // Unix nanoseconds.

      <w>nondeterministic</w>
      <w>nullable</w>
      <w>overridable</w>
      <w>pseudocode</w>
      <w>substitutor</w>
      <w>subtyping</w>
      <w>supertype</w>
      <w>supertypes</w>
      <w>tuple</w>
      <w>unary</w>
    </words>
  </dictionary>

        # Store the path to be able to re-generate a dependable from it in overrides
        self.path = path
        # Save the cache key at creation to optimize performance

          exchange.responseHeadersStart()
          invokeStartEvent = false
        }
        if (responseBuilder == null) {
          if (requestBody.isDuplex()) {
            // Prepare a duplex body so that the application can send a request body later.
            exchange.flushRequest()
            val bufferedRequestBody = exchange.createRequestBody(request, true).buffer()

注意，变量 `item` 是列表 `items` 中的元素之一。

而且，编辑器仍然知道它是一个 `str`，并为此提供了支持。

#### 元组和集合

声明 `tuple` 和 `set` 的方法也是一样的：

```Python hl_lines="1  4"
{!../../../docs_src/python_types/tutorial007.py!}
```

这表示：

* 变量 `items_t` 是一个 `tuple`，其中的前两个元素都是 `int` 类型, 最后一个元素是 `str` 类型。
* 变量 `items_s` 是一个 `set`，其中的每个元素都是 `bytes` 类型。

#### 字典

定义 `dict` 时，需要传入两个子类型，用逗号进行分隔。

import kotlin.test.assertFailsWith
import mockwebserver3.MockResponse
import mockwebserver3.MockWebServer
import mockwebserver3.SocketPolicy.DoNotReadRequestBody
import okhttp3.Headers.Companion.headersOf
import okhttp3.internal.duplex.AsyncRequestBody
import okhttp3.internal.http2.ErrorCode
import okhttp3.testing.PlatformRule
import okio.BufferedSink
import okio.IOException
import org.junit.jupiter.api.BeforeEach
import org.junit.jupiter.api.Disabled

  // for computing gradient so we could safely drop it.
  outputs[0] = temp_outputs[1];
  temp_outputs[0]->Unref();
  return absl::OkStatus();
}

class CppGradients
    : public ::testing::TestWithParam<std::tuple<const char*, bool, bool>> {
 protected:
  void SetUp() override {
    TF_StatusPtr status(TF_NewStatus());
    TF_SetTracingImplementation(std::get<0>(GetParam()), status.get());