BExISMigration.PrimaryData.oldIdsIntoExtra C# (CSharp) Method

        private XmlDocument oldIdsIntoExtra(long obsId, string dataSetID, XmlNode existExtra)
        {
            XmlDocument newExtra = new XmlDocument();
            if (existExtra != null)
            {
                newExtra.LoadXml(existExtra.OuterXml);
            }
            else
            {
                XmlElement root = newExtra.CreateElement("extra");
                newExtra.AppendChild(root);
            }
            XmlElement obsid = newExtra.CreateElement("obsid");
            obsid.InnerText = obsId.ToString();
            newExtra.DocumentElement.AppendChild(obsid);
            XmlElement datid = newExtra.CreateElement("oldBExISdatasetId");
            datid.InnerText = dataSetID;
            newExtra.DocumentElement.AppendChild(datid);

            return newExtra;
        }