public async Task <Customer> AddCustomerAsync(Customer customer)
        {
            context.Customers.Add(customer);
            await context.SaveChangesAsync();

            return(customer);
        }
        public async Task <Order> AddOrderAsync(Order order)
        {
            _context.Orders.Add(order);
            await _context.SaveChangesAsync();

            return(order);
        }
        public async Task <PrincipalPart> AddPrincipalPartAsync(PrincipalPart principalPart)
        {
            _context.PrincipalParts.Add(principalPart);
            await _context.SaveChangesAsync();

            return(principalPart);
        }