code: func (*Service) ListVLANs(c context.Context, req *crimson.ListVLANsRequest) (*crimson.ListVLANsResponse, error) {
  	ids := make(map[int64]struct{}, len(req.Ids))
  	for _, id := range req.Ids {
  		ids[id] = struct{}{}
  	}
  	vlans, err := listVLANs(c, ids, stringset.NewFromSlice(req.Aliases...))
  	if err != nil {
  		return nil, err
  	}
  	return &crimson.ListVLANsResponse{
  		Vlans: vlans,
  	}, nil
  }
docs: // ListVLANs handles a request to retrieve VLANs.