mux.Handle("/", traceviewer.MainHandler([]traceviewer.View{
		{Type: traceviewer.ViewProc, Ranges: ranges},
		// N.B. Use the same ranges for threads. It takes a long time to compute
		// the split a second time, but the makeup of the events are similar enough
		// that this is still a good split.
		{Type: traceviewer.ViewThread, Ranges: ranges},
	}))

	// Catapult handlers.
	mux.Handle("/trace", traceviewer.TraceHandler())

		t0 = ti
	}
	if base[b0:bi] == ".." {
		return "", errors.New("Rel: can't make " + targpath + " relative to " + basepath)
	}
	if b0 != bl {
		// Base elements left. Must go up before going down.
		seps := bytealg.CountString(base[b0:bl], Separator)
		size := 2 + seps*3
		if tl != t0 {
			size += 1 + tl - t0
		}
		buf := make([]byte, size)
		n := copy(buf, "..")
		for i := 0; i < seps; i++ {

	if size <= maxStackArgs {
		// as long as makeArgs is inlined, these will be stack-allocated
		argVals = make([]Value, size, maxStackArgs)
		argRefs = make([]ref, size, maxStackArgs)
	} else {
		// allocates on the heap, but exceeding maxStackArgs should be rare
		argVals = make([]Value, size)
		argRefs = make([]ref, size)
	}
	return
}

// storeArgs maps input args onto respective Value and ref slices.

			CheckCertificatePeriodValidity(ca.BaseName, caCert)

			// Cert exists already, make sure it's valid
			if !caCert.IsCA {
				return errors.Errorf("certificate %q is not a CA", ca.Name)
			}
			// Try and load a CA Key
			caKey, err = pkiutil.TryLoadKeyFromDisk(ic.CertificatesDir, ca.BaseName)
			if err != nil {
				// If there's no CA key, make sure every certificate exists.
				for _, leaf := range leaves {

		// Use smaller heap for Windows/ARM to avoid crash.
		heap = 100 << 20
	}
	if testing.Short() {
		heap = 100 << 20
	}
	// This makes fork slower.
	garbage := make([]byte, heap)
	// Need to touch the slice, otherwise it won't be paged in.
	done := make(chan bool)
	go func() {
		for i := range garbage {
			garbage[i] = 42
		}
		done <- true
	}()
	<-done

	var prof bytes.Buffer

		}
	}

	if s.Broadcaster != nil {
		stopCh := make(chan struct{})
		s.Broadcaster.StartRecordingToSink(stopCh)
	}

	// TODO(thockin): make it possible for healthz and metrics to be on the same port.

	var healthzErrCh, metricsErrCh chan error
	if s.Config.BindAddressHardFail {
		healthzErrCh = make(chan error)
		metricsErrCh = make(chan error)
	}

	// Start up a healthz server if requested

> Modern versions of Python have support for **"asynchronous code"** using something called **"coroutines"**, with **`async` and `await`** syntax.

That should make more sense now. ✨

All that is what powers FastAPI (through Starlette) and what makes it have such an impressive performance.

## Very Technical Details

!!! warning
    You can probably skip this.

I'll give you more concrete examples in the next chapters.

## Restarts

Similar to making sure your application is run on startup, you probably also want to make sure it is **restarted** after failures.

### We Make Mistakes

We, as humans, make **mistakes**, all the time. Software almost *always* has **bugs** hidden in different places. 🐛

			opts.mode = traceviewer.ModeGoroutineOriented
			opts.setTask(parsed, task)

			// Pick the goroutine to orient ourselves around by just
			// trying to pick the earliest event in the task that makes
			// any sense. Though, we always want the start if that's there.
			var firstEv *trace.Event
			if task.Start != nil {
				firstEv = task.Start
			} else {
				for _, logEv := range task.Logs {

// to b is the total duration during which the mutator utilization was
// in the range [a, b].
//
// This distribution is *not* normalized (it is not a probability
// distribution). This makes it easier to work with as it's being
// updated.
//
// It is represented as the sum of scaled uniform distribution
// functions and Dirac delta functions (which are treated as
// degenerate uniform distributions).