code: public XceliteSheet getSheet(String sheetName) {
      Sheet sheet = workbook.getSheet(sheetName);
      if (sheet == null) {
        throw new XceliteException(String.format("Could not find sheet named \"%s\"", sheetName));
      }
      return new XceliteSheetImpl(sheet, file);
    }
docs: Gets the sheet with the specified index.
  
  @param sheetIndex the sheet name
  @return XceliteSheet object