public TrainingElement Pop()
        {
            TrainingElement first = ToDo.FirstOrDefault(te => te.TotalCount > te.TrainingStarted);

            if (first != null)
            {
                //first.TrainingStarted++;
                return(first);
            }
            return(null);
        }
        public void Push(Troop troop, int nb = 1)
        {
            _cumulTime = null;
            TrainingElement first = ToDo.FirstOrDefault(te => te.Troop == troop);

            if (first == null)
            {
                ToDo.Add(new TrainingElement(troop, nb));
            }
            else
            {
                first.TotalCount += nb;
            }
        }