code: func (*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
  	}
  	q := datastore.NewQuery(model.ConfigKind)
  	if err := datastore.Run(c, q, func(cfg *model.Config, f datastore.CursorCB) error {
  		rsp.Configs = append(rsp.Configs, &cfg.Config)
  		return nil
  	}); err != nil {
  		return nil, errors.Annotate(err, "failed to fetch configs").Err()
  	}
  	return rsp, nil
  }
docs: // List handles a request to list all configs.