public void TestTemplateMethod()
        {
            var excelExporter = new ExcelExporter();

            excelExporter.ExportFormattedData();

            // OUTPUT: Reading data from external source.

            // OUTPUT: Formatting data.

            // OUTPUT: Exporting data to Excel file.

            var pdfExporter = new PdfExporter();

            pdfExporter.ExportFormattedData();

            // OUTPUT: Reading data from external source.

            // OUTPUT: Formatting data.

            // OUTPUT: Exporting data to PDF file.
        }