code: func (resp *QueryResponse) MarshalJSON() ([]byte, error) {
  	if resp.Err != nil {
  		return json.Marshal(struct {
  			Err string `json:"error"`
  		}{Err: resp.Err.Error()})
  	}
  
  	return json.Marshal(struct {
  		Results        []interface{}    `json:"results"`
  		ColumnAttrSets []*ColumnAttrSet `json:"columnAttrs,omitempty"`
  	}{
  		Results:        resp.Results,
  		ColumnAttrSets: resp.ColumnAttrSets,
  	})
  }
docs: // MarshalJSON marshals QueryResponse into a JSON-encoded byte slice