public static string GetRecurrenceExpression()
            {
                var startDate = new DateTime(2013, 3, 1);
                var recursUntil = new DateTime(2013, 3, 3);
                var duration = TimeSpan.FromMinutes(30);
                var maxOccurrences = 0;
                var interval = 1;
                IRecurrenceDescriptor dailyDescriptor = null;
     
                var rrBuilder = new RecurrenceRuleBuilder();
                var dailyExpression = rrBuilder.CreateDailyRecurrenceExpression(startDate, duration, recursUntil, maxOccurrences, interval);
     
                //if isParsed returns true the iCal daily recurrence expression is parsed
                var isParsed = rrBuilder.TryParseRecurrenceExpression(dailyExpression, out dailyDescriptor);
     
                string dailyExpressionReParsed = rrBuilder.GetRecurrenceExpression(dailyDescriptor);
                return dailyExpression;
            }