if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
		type event struct {
			WhenString string
			Elapsed    time.Duration
			Goroutine  trace.GoID
			What       string
			// TODO: include stack trace of creation time
		}
		type task struct {
			WhenString string
			ID         trace.TaskID
			Duration   time.Duration
			Complete   bool

			case traceGoRunning, traceGoSyscall:
				if getg() == gp || mp.curg == gp {
					break
				}
				fallthrough
			default:
				print("runtime: gp=", unsafe.Pointer(gp), " gp.goid=", gp.goid, " status=", gStatusStrings[status], "\n")
				throw("attempted to trace stack of a goroutine this thread does not own")
			}
		}
	}

	if gp != nil && mp == nil {

			status = GoWaiting
		}
		s = goStateTransition(GoID(e.base.args[0]), GoNotExist, status)
		s.Stack = Stack{table: e.table, id: stackID(e.base.args[1])}
	case go122.EvGoCreateSyscall:
		s = goStateTransition(GoID(e.base.args[0]), GoNotExist, GoSyscall)
	case go122.EvGoStart:
		s = goStateTransition(GoID(e.base.args[0]), GoRunnable, GoRunning)
	case go122.EvGoDestroy:

			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		// Collect all the regions with their goroutines.
		type region struct {
			*trace.UserRegionSummary
			Goroutine           trace.GoID
			NonOverlappingStats map[string]time.Duration
			HasRangeTime        bool
		}
		var regions []region
		var maxTotal time.Duration
		validNonOverlappingStats := make(map[string]struct{})

			s := suspendG(gp)
			if !s.dead {
				ug.goid = s.g.goid
				if s.g.m != nil {
					ug.mid = int64(s.g.m.procid)
				}
				ug.status = readgstatus(s.g) &^ _Gscan
				ug.waitreason = s.g.waitreason
				ug.inMarkAssist = s.g.inMarkAssist
				ug.stackID = traceStack(0, gp, gen)
			}
			resumeG(s)
			casgstatus(me, _Gwaiting, _Grunning)
		})
		if ug.goid != 0 {
			untracedGs = append(untracedGs, ug)
		}

		// time at which procs changed.
		time int64
		// n is the number of procs at that point.
		n int
	}
	out := [][]MutatorUtil{}
	stw := 0
	ps := []perP{}
	inGC := make(map[GoID]bool)
	states := make(map[GoID]GoState)
	bgMark := make(map[GoID]bool)
	procs := []procsCount{}
	seenSync := false

	// Helpers.
	handleSTW := func(r Range) bool {
		return flags&UtilSTW != 0 && isGCSTW(r)
	}

// lowest first.
func emitTask(ctx *traceContext, task *trace.UserTaskSummary, sortIndex int) {
	// Collect information about the task.
	var startStack, endStack trace.Stack
	var startG, endG trace.GoID
	startTime, endTime := ctx.startTime, ctx.endTime
	if task.Start != nil {
		startStack = task.Start.Stack()
		startG = task.Start.Goroutine()
		startTime = task.Start.Time()
	}
	if task.End != nil {

	return [20]int{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}
}

func TestTracebackParentChildGoroutines(t *testing.T) {
	parent := fmt.Sprintf("goroutine %d", runtime.Goid())
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		buf := make([]byte, 1<<10)
		// We collect the stack only for this goroutine (by passing

	//    param may point to a savedOpenDeferState.
	param        unsafe.Pointer
	atomicstatus atomic.Uint32
	stackLock    uint32 // sigprof/scang lock; TODO: fold in to atomicstatus
	goid         uint64
	schedlink    guintptr
	waitsince    int64      // approx time when the g become blocked
	waitreason   waitReason // if status==Gwaiting

		// the runtime was generating extraneous events.
		const (
			entered = iota
			blocked
			runnable
			running
		)
		gs := make(map[trace.GoID]int)
		seenSpecialGoroutines := false
		r, err := trace.NewReader(bytes.NewReader(tb))
		if err != nil {
			t.Error(err)
		}
		for {
			ev, err := r.ReadEvent()
			if err == io.EOF {
				break