code: func (s *ClusterConfigurationService) SetStaticTokens(c services.StaticTokens) error {
  	value, err := services.GetStaticTokensMarshaler().Marshal(c)
  	if err != nil {
  		return trace.Wrap(err)
  	}
  	_, err = s.Put(context.TODO(), backend.Item{
  		Key:     backend.Key(clusterConfigPrefix, staticTokensPrefix),
  		Value:   value,
  		Expires: c.Expiry(),
  		ID:      c.GetResourceID(),
  	})
  	if err != nil {
  		return trace.Wrap(err)
  	}
  
  	return nil
  }
docs: // SetStaticTokens sets the list of static tokens used to provision nodes.