code: func (c *Controller) List(filterStrings ...string) ([]Worker, error) {
  	filter, err := filters.ParseAll(filterStrings...)
  	if err != nil {
  		return nil, err
  	}
  	var workers []Worker
  	c.workers.Range(func(k, v interface{}) bool {
  		w := v.(Worker)
  		if filter.Match(adaptWorker(w)) {
  			workers = append(workers, w)
  		}
  		return true
  	})
  	return workers, nil
  }
docs: // List lists workers