code: func (r rawResponse) result() (result []byte, err error) {
  	if r.Error != nil {
  		return nil, r.Error
  	}
  	return r.Result, nil
  }
docs: // result checks whether the unmarshaled response contains a non-nil error,
  // returning an unmarshaled btcjson.RPCError (or an unmarshaling error) if so.
  // If the response is not an error, the raw bytes of the request are
  // returned for further unmashaling into specific result types.