public void AddTester(Tester t)
        {
            int minAge, maxAge;

            try
            {
                minAge = (int)instance.GetConfig("Tester minimum age");
                maxAge = (int)instance.GetConfig("Tester maximun age");
            }
            catch (AccessViolationException e)
            {
                throw e;
            }
            catch (KeyNotFoundException e)
            {
                throw e;
            }
            int testerAge = (DateTime.Now.Year - t.DateOfBirth.Year);

            if (testerAge < minAge || testerAge > maxAge)
            {
                throw new ArgumentOutOfRangeException("Tester age is not on range of " + minAge + "-" + maxAge);
            }
            else
            {
                try
                {
                    instance.AddTester(CreateDOFromBO.CreateDOTester(t));
                }
                catch (KeyNotFoundException e)
                {
                    throw e;
                }
            }
        }
        public void UpdateTesterDetails(Tester t)
        {
            bool exist = GetTestersList().Exists(x => x.Id == t.Id);

            if (!exist)
            {
                throw new KeyNotFoundException("Can't update this tester becauze he is not on the system.");
            }
            else
            {
                try
                {
                    instance.UpdateTesterDetails(CreateDOFromBO.CreateDOTester(t));
                }
                catch (KeyNotFoundException e)
                {
                    throw e;
                }
            }
        }