code: func (srv *Config) List(c context.Context, req *config.ListRequest) (*config.ListResponse, error) {
  	rsp := &config.ListResponse{}
  	// TODO(smut): Handle page tokens.
  	if req.GetPageToken() != "" {
  		return rsp, nil
  	}
  	srv.cfg.Range(func(_, val interface{}) bool {
  		rsp.Configs = append(rsp.Configs, val.(*config.Config))
  		return true
  	})
  	return rsp, nil
  }
docs: // List handles a request to list all configs.