public Document(String fileName)
        {
            this.FileName = fileName;
            docFileName = fileName + ".docx";

            packager = DocumentPackager.GetInstance();
            docxFile = packager.CreateDocument(docFileName);
            body = packager.GetBody();
        }
 internal static DocumentPackager GetInstance()
 {
     if (_instance == null) _instance = new DocumentPackager();
     return _instance;
 }