public override IEnumerable <IXmlChange> Changes(XmlModel model)
        {
            var vsXmlModel = model as VSXmlModel;

            Debug.Assert(vsXmlModel != null);
            if (vsXmlModel != null)
            {
                var internalModel = vsXmlModel.XmlModel;
                foreach (var modelChange in _editorTransaction.Changes(internalModel))
                {
                    yield return(GetXmlChange(modelChange));
                }
            }
        }