code: func (w *Writer) Levels() map[string]string {
  	w.mutex.Lock()
  	defer w.mutex.Unlock()
  
  	if w.levels == nil {
  		w.setLevels(Levels)
  	}
  	levels := make(map[string]string)
  	for level, effect := range w.levels {
  		levels[level] = effect
  	}
  
  	return levels
  }
docs: // Levels returns a list of levels and their associated actions.