private void OnSessionValueChanged(object s, ValueChangedEventArgs e)
        {
            switch (e.Key)
            {
                case Session.CycleTime:
                    OnCycleTimeChanged(e);
                    break;

                case Session.FinishHimTime:
                    OnFinishHimTimeChanged();
                    break;
            }
        }
        private void OnCycleTimeChanged(ValueChangedEventArgs e)
        {
            OnPropertyChanged("ValueForCycleTime");

            var cycleTime = (TimeSpan)e.NewValue;
            var finishHimTime = _session.Get<TimeSpan>(Session.FinishHimTime);

            if (finishHimTime.Subtract(cycleTime).TotalSeconds < 0)
                _session.Set(Session.FinishHimTime, cycleTime);
        }