func (records *Records) Declare() error {
	_, err := csomItemRecordMethod(records.item, "DeclareItemAsRecord", nil, records.item.config)
	return err
}
Declare declares this item as a record (CSOM helper)
package api
import (
	"bytes"
	"encoding/json"
	"fmt"
	"strconv"
	"strings"
	"time"
	"github.com/koltyakov/gosip/csom"
)
type Records struct {
	item *Item
}
func NewRecords(item *Item) *Records {
	return &Records{item: item}
}
func (records *Records) IsRecord() (bool, error) {
	date, err := records.RecordDate()
	if err != nil {
		return false, err
	}
	if fmt.Sprintf("%s", date) == "0001-01-01 00:00:00 +0000 UTC" {
		return false, nil
	}
	return true, nil
}
func (records *Records) RecordDate() (time.Time, error) {
	data, err := records.item.Select("OData__vti_ItemDeclaredRecord").Get()
	if err != nil {
		if strings.Index(err.Error(), "OData__vti_ItemDeclaredRecord") != -1 {
			return time.Time{}, nil  
		}
		return time.Time{}, err
	}
	res := &struct {
		RecordDate time.Time `json:"OData__vti_ItemDeclaredRecord"`
	}{}
	data = NormalizeODataItem(data)
	if err := json.Unmarshal(data, &res); err != nil {
		return time.Time{}, err
	}
	return res.RecordDate, nil
}