code: func NewBuilder(replicaCount int) *Builder {
  	if replicaCount < 1 {
  		replicaCount = 1
  	}
  	if replicaCount > 127 {
  		replicaCount = 127
  	}
  	b := &Builder{ring: lowring.New(replicaCount), randIntn: rand.New(rand.NewSource(0)).Intn}
  	b.groups = []*BuilderGroup{{builder: b}}
  	return b
  }
docs: // NewBuilder creates a new builder with the initial replica count given.