code: func (r *Router) GetDatacenters() []string {
  	r.RLock()
  	defer r.RUnlock()
  
  	dcs := make([]string, 0, len(r.managers))
  	for dc := range r.managers {
  		dcs = append(dcs, dc)
  	}
  
  	sort.Strings(dcs)
  	return dcs
  }
docs: // GetDatacenters returns a list of datacenters known to the router, sorted by
  // name.