code: func (h *Hooks) Append(other *Hooks) error {
  	for _, hook := range *other {
  		if h.Match(hook.ID) != nil {
  			return fmt.Errorf("hook with ID %s is already defined", hook.ID)
  		}
  
  		*h = append(*h, hook)
  	}
  
  	return nil
  }
docs: // Append appends hooks unless the new hooks contain a hook with an ID that already exists