public void Delete(CrudRest.Entity.Customer customer)
        {
            if (customer == null)
            {
                throw new NullReferenceException("customer");
            }

            _data.Remove(customer);
        }
        public void Insert(CrudRest.Entity.Customer customer)
        {
            if (customer == null)
            {
                throw new NullReferenceException("customer");
            }

            _data.Add(customer);
        }
        public void Update(CrudRest.Entity.Customer customer)
        {
            if (customer == null)
            {
                throw new NullReferenceException("customer");
            }

            var customerFound = (from c in _data
                                 where c.Id == customer.Id
                                 select c).FirstOrDefault();

            if (customerFound == null)
            {
                return;
            }

            _data.Remove(customer);
            _data.Add(customer);
        }