code: func Register(name string, dsInit DatastoreInit, dsVersion DatastoreVersion) error {
  	lock.Lock()
  	defer lock.Unlock()
  	if _, exists := datastores[name]; exists {
  		return fmt.Errorf("Datastore provider %q is already registered", name)
  	}
  	datastores[name] = dsInit
  
  	if _, exists := datastoreVersions[name]; exists {
  		return fmt.Errorf("Datastore provider's %q version function already registered", name)
  	}
  	datastoreVersions[name] = dsVersion
  	return nil
  }
docs: // Register adds specified datastore backend to the list of options.