code: func (b RowResult) MarshalJSON() ([]byte, error) {
  	columns := b.Columns
  	if columns == nil {
  		columns = []uint64{}
  	}
  	keys := b.Keys
  	if keys == nil {
  		keys = []string{}
  	}
  	return json.Marshal(struct {
  		Attributes map[string]interface{} `json:"attrs"`
  		Columns    []uint64               `json:"columns"`
  		Keys       []string               `json:"keys"`
  	}{
  		Attributes: b.Attributes,
  		Columns:    columns,
  		Keys:       keys,
  	})
  }
docs: // MarshalJSON serializes this row result.