doneCh := make(chan error, 1)
	defer xioutil.SafeClose(doneCh)

	// Save rebalance.bin periodically.
	go func() {
		// Update rebalance.bin periodically once every 5-10s, chosen randomly
		// to avoid multiple pool leaders herding to update around the same
		// time.
		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		randSleepFor := func() time.Duration {

And `fastapi-slim` would not include those standard dependencies.

Now `fastapi` doesn't include those standard dependencies unless you install with `pip install "fastapi[standard]"`.

Before, you would install `pip install fastapi`, now you should include the `standard` optional dependencies (unless you want to exclude one of those): `pip install "fastapi[standard]"`.