func (i HandlerID) String() string {
	if i >= HandlerID(len(_HandlerID_index)-1) {
		return "HandlerID(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _HandlerID_name[_HandlerID_index[i]:_HandlerID_index[i+1]]

//
//go:generate msgp -unexported -file=$GOFILE
//go:generate stringer -type=Op -output=msg_string.go -trimprefix=Op $GOFILE

// Op is operation type messages.
type Op uint8

// HandlerID is the ID for the handler of a specific type.
type HandlerID uint8

const (
	// OpConnect is a connect request.
	OpConnect Op = iota + 1

	// OpConnectResponse is a response to a connect request.
	OpConnectResponse

}

// RegisterSingleHandler will register a stateless handler that serves
// []byte -> ([]byte, error) requests.
// subroutes are joined with "/" to a single subroute.
func (m *Manager) RegisterSingleHandler(id HandlerID, h SingleHandlerFn, subroute ...string) error {
	if !id.valid() {
		return ErrUnknownHandler
	}
	s := strings.Join(subroute, "/")
	if debugPrint {

From this connection individual requests can be made.

Each handler, with optional subroutes can be registered with the manager using 
`Manager.RegisterXHandler(handlerID, handler, subroutes...)`.

A `Handler()` function provides an HTTP handler, which should be hooked up to the appropriate route on the server.

	Local     string
	Remote    string
	Subroute  string
}

const (
	httpScheme  = "http://"
	httpsScheme = "https://"
)

func (c *muxClient) traceRoundtrip(ctx context.Context, t *tracer, h HandlerID, req []byte) ([]byte, error) {
	if t == nil || t.Publisher.NumSubscribers(t.TraceType) == 0 {
		return c.roundtrip(h, req)
	}

	// Following trimming is needed for consistency between outputs with other internode traces.

	lockRPCUnlock      = newLockHandler(grid.HandlerLockUnlock)
	lockRPCRLock       = newLockHandler(grid.HandlerLockRLock)
	lockRPCRUnlock     = newLockHandler(grid.HandlerLockRUnlock)
)

func newLockHandler(h grid.HandlerID) *grid.SingleHandler[*dsync.LockArgs, *dsync.LockResp] {
	return grid.NewSingleHandler[*dsync.LockArgs, *dsync.LockResp](h, func() *dsync.LockArgs {
		return &dsync.LockArgs{}
	}, func() *dsync.LockResp {