code: func (r *AddressRange) MarshalJSON() ([]byte, error) {
  	m := map[string]interface{}{
  		"Sub":   r.Sub.String(),
  		"Start": r.Start,
  		"End":   r.End,
  	}
  	return json.Marshal(m)
  }
docs: // MarshalJSON returns the JSON encoding of the Range object