code: func ListCAs(c context.Context) ([]string, error) {
  	keys := []*ds.Key{}
  	q := ds.NewQuery("CA").Eq("Removed", false).KeysOnly(true)
  	if err := ds.GetAll(c, q, &keys); err != nil {
  		return nil, transient.Tag.Apply(err)
  	}
  	names := make([]string, len(keys))
  	for i, key := range keys {
  		names[i] = key.StringID()
  	}
  	return names, nil
  }
docs: // ListCAs returns names of all currently active CAs, in no particular order.