Itenso.TimePeriod.TimePeriodCollection.GetDuration C# (CSharp) Method

        protected TimeSpan? GetDuration()
        {
            DateTime? start;
            DateTime? end;

            GetStartEnd( out start, out end );

            if ( start == null || end == null )
            {
                return null;
            }

            return end.Value - start.Value;
        }