public override string GetFormat(object value, string format)
        {
            var styles = _package.Workbook.Styles;

            ExcelNumberFormatXml.ExcelFormatTranslator ft = null;
            foreach (var f in styles.NumberFormats)
            {
                if (f.Format == format)
                {
                    ft = f.FormatTranslator;
                    break;
                }
            }
            if (ft == null)
            {
                ft = new ExcelNumberFormatXml.ExcelFormatTranslator(format, -1);
            }
            return(ExcelRangeBase.FormatValue(value, ft, format, ft.NetFormat));
        }