public void DeleteItems()
        {
            if (_customersToDelete == null || _customersToDelete.Count <= 0)
            {
                var reason = _customersToDelete == null
                        ? "null" : "equal or less than zero";
                var message = string.Format("Deletion could not be executed " +
                                            "because to the internal list being {0}", reason);
                throw new PetsEntityException(message);
            }

            try
            {
                using (PetShopDBContext _dbContext = new PetShopDBContext())
                {
                    //_dbContext.Customers.RemoveRange(_customersToDelete);
                    _dbContext.TagEntitiesAsDeleted <Customer>(_customersToDelete);
                    _dbContext.SaveChanges();
                    _customersToDelete.Clear();
                }
            }
            catch (Exception exception)
            {
                // logging here
                throw;
            }
        }