DDay.iCal.iCalDateTime.GetTimeZoneObservance C# (CSharp) Method

        private TimeZoneObservance? GetTimeZoneObservance()
        {
            if (_TimeZoneObservance == null &&
                TZID != null &&
                Calendar != null)
            {
                ITimeZone tz = Calendar.GetTimeZone(TZID);
                if (tz != null)
                    _TimeZoneObservance = tz.GetTimeZoneObservance(this);
            }
            return _TimeZoneObservance;
        }