code: func (d *driver) initStore(option map[string]interface{}) error {
  	if data, ok := option[netlabel.LocalKVClient]; ok {
  		var err error
  		dsc, ok := data.(discoverapi.DatastoreConfigData)
  		if !ok {
  			return types.InternalErrorf("incorrect data in datastore configuration: %v", data)
  		}
  		d.store, err = datastore.NewDataStoreFromConfig(dsc)
  		if err != nil {
  			return types.InternalErrorf("macvlan driver failed to initialize data store: %v", err)
  		}
  
  		return d.populateNetworks()
  	}
  
  	return nil
  }
docs: // initStore drivers are responsible for caching their own persistent state