code: func ParseRangeList(str string) (*RangeList, error) {
  	rl := RangeList{}
  	if len(str) == 0 {
  		return &rl, nil
  	}
  	parts := strings.Split(str, ",")
  	for _, p := range parts {
  		r, err := ParseRange(p)
  		if err != nil {
  			return nil, err
  		}
  		rl = append(rl, r)
  	}
  	return &rl, nil
  }
docs: // ParseRangeList parses a string that contains a comma-separated list of ranges