public IActionResult Edit(int id)
        {
            var customerExists = customers.Exists(id);

            if (!customerExists)
            {
                return(RedirectToAction(nameof(All), new { order = "ascending" }));
            }

            var customer = this.customers.ById(id);

            var vm = new CustomerFormModel()
            {
                Id            = customer.Id,
                Name          = customer.Name,
                BirthDate     = customer.BirthDate,
                IsYoungDriver = customer.IsYoungDriver
            };

            return(View(vm));
        }