public static string AddressR1C1(this ExcelReference range) { if (range.IsSingleCell()) { return(AddressParser.ToAddressR1C1(range.RowFirst, range.ColumnLast)); } return($"{AddressParser.ToAddressR1C1(range.RowFirst, range.ColumnFirst)}:{AddressParser.ToAddressR1C1(range.RowLast, range.ColumnLast)}"); }