public static bool IsHoliday(DateTime dateTime, Country country = Country.Cz) { var isNationalDay = false; var nationalDays = Holidays.GetHolidayDaysByCountry(country, dateTime.Year); if (nationalDays != null) { isNationalDay = Holidays.GetHolidayDaysByCountry(country, dateTime.Year) .Any(h => h.Month == dateTime.Month && h.Day == dateTime.Day); } return(isNationalDay); }