* that trigger this are HEADERS and PUSH_PROMISE.
     *
     * @param inFinished true if the sender will not send further frames.
     * @param streamId the stream owning these headers.
     * @param associatedStreamId the stream that triggered the sender to create this stream.
     */
    fun headers(
      inFinished: Boolean,
      streamId: Int,
      associatedStreamId: Int,

   *
   * @since 8.0
   */
  public static final byte ENQ = 5;

  /**
   * Acknowledge: A communication control character transmitted by a receiver as an affirmative
   * response to a sender.
   *
   * @since 8.0
   */
  public static final byte ACK = 6;

  /**
   * Bell ('\a'): A character for use when there is a need to call for human attention. It may

            putValue(data, "Message-Number", message.getMessageNumber());
            putValue(data, "Received-Date", getReceivedDate(message));
            putValue(data, "Reply-To", message.getReplyTo());
            putValue(data, "Sender", message.getSender());
            putValue(data, "Sent-Date", message.getSentDate());
            putValue(data, "Size", message.getSize());
            putValue(data, "Subject", message.getSubject());

	m.Flags &^= FlagPayloadIsZero
	if len(m.Payload) == 0 && m.Payload != nil {
		m.Flags |= FlagPayloadIsZero
	}
}

type receiver interface {
	msgp.Unmarshaler
	Op() Op
}

type sender interface {
	msgp.MarshalSizer
	Op() Op
}

type connectReq struct {
	ID    [16]byte
	Host  string
	Time  time.Time
	Token string
}

	go func() {
		wg.Wait()
		defer xioutil.SafeClose(send)
		err := m.handleRequests(ctx, msg, send, handler, handlerIn)
		if err != nil {
			handlerErr.Store(err)
		}
	}()

	// Response sender goroutine...
	go func(outBlock <-chan struct{}) {
		wg.Wait()
		defer m.parent.deleteMux(true, m.ID)
		m.sendResponses(ctx, send, c, &handlerErr, outBlock)
	}(m.outBlock)

	// Remote aliveness check if needed.

	}
	if !m.respMu.TryLock() {
		// Cancel before locking - will unblock any pending sends.
		if m.cancelFn != nil {
			m.cancelFn(context.Canceled)
		}
		// Wait for senders to release.
		m.respMu.Lock()
	}

	defer m.respMu.Unlock()
	m.closeLocked()
}

func (m *muxClient) closeLocked() {
	if m.closed {
		return
	}

			return
		}
	}

	// Check if we are creating svc account for request sender.
	isSvcAccForRequestor := false
	if targetUser == requestorUser || targetUser == requestorParentUser {
		isSvcAccForRequestor = true
	}

	// If we are creating svc account for request sender, ensure
	// that targetUser is a real user (i.e. not derived
	// credentials).
	if isSvcAccForRequestor {

// implied by the type argument.
func clear[T ~[]Type | ~map[Type]Type1](t T)

// The close built-in function closes a channel, which must be either
// bidirectional or send-only. It should be executed only by the sender,
// never the receiver, and has the effect of shutting down the channel after
// the last sent value is received. After the last value has been received
// from a closed channel c, any receive from c will succeed without

      }
      flowControlListener.receivingConnectionWindowChanged(readBytes)
    }
  }

  /**
   * Returns a new server-initiated stream.
   *
   * @param associatedStreamId the stream that triggered the sender to create this stream.
   * @param out true to create an output stream that we can use to send data to the remote peer.
   *     Corresponds to `FLAG_FIN`.
   */
  @Throws(IOException::class)
  fun pushStream(

		// Returning error here is too noisy.
		return nil
	case c.outQueue <- msg:
		return nil
	}
}

// queueMsg queues a message, with an optional payload.
// sender should not reference msg.Payload
func (c *Connection) queueMsg(msg message, payload sender) error {
	// Add baseflags.
	msg.Flags.Set(c.baseFlags)
	// This cannot encode subroute.
	msg.Flags.Clear(FlagSubroute)
	if payload != nil {