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        private static readonly Tuple<int, int>[] staticHolidays = new Tuple<int, int>[] {
            new Tuple<int, int>(1,1),
            new Tuple<int, int>(1,6),
            new Tuple<int, int>(5,1),
            new Tuple<int, int>(8,15),
            new Tuple<int, int>(10,26),
            new Tuple<int, int>(11,1),
            new Tuple<int, int>(12,8),
            new Tuple<int, int>(12,25),
            new Tuple<int, int>(12,26),
        };

        // Feiertage für WIEN
        private static bool IsHoliday(DateTime date)
        {
            if (date > DateTime.MinValue)
            {
                foreach (var monthDay in staticHolidays)
                    if (date.Month == monthDay.Item1 && date.Day == monthDay.Item2)
                        return true;
                
                DateTime easter = EasterGregDate(date.Year);
                sbyte[] easterDiff = { -2, 1, 39, 50, 60 };
                // Ostersonntag - 2   = Karfreitag 
                // Ostersonntag + 1   = Ostermontag 
                // Ostersonntag + 39  = Christi Himmelfahrt 
                // Ostersonntag + 50  = Pfingstmontag 
                // Ostersonntag + 60  = Fronleichnam 

                for (int i = 0; i < easterDiff.Length; i++)
                    if (date == easter.AddDays(easterDiff[i]))
                        return true;
            }
            return false;
        }