Represents the information needed when creating a purchase voucher.
Inheritance: DineroEntity
        /// <summary>
        /// Add the purchase voucher to the organization's invoices.
        /// </summary>
        /// <param name="modelToCreate">The purchase voucher to create</param>
        public Task<PurchaseVoucherCreateResult> AddAsync(PurchaseVoucherCreate modelToCreate)
        {
            var parameters = new Dictionary<string, string>
            {
                {DineroApiParameterName.Endpoint, "vouchers/purchase"}
            };

            return Dinero.PostAsync<PurchaseVoucherCreateResult>(parameters, modelToCreate.JSonify());
        }
        public static async Task AddNewPurchaseVoucher(Dinero dinero)
        {
            var model = new PurchaseVoucherCreate
            {
                VoucherDate = "2015-12-02",
                Notes = "Some very important notes!"
            };

            var createdResult = await dinero.PurchaseVouchers.AddAsync(model);
            Console.WriteLine("Voucher created. New voucher id: " + createdResult.VoucherGuid);
        } 
 /// <summary>
 /// Add the purchase voucher to the organization's invoices.
 /// </summary>
 /// <param name="modelToCreate">The purchase voucher to create</param>
 public PurchaseVoucherCreateResult Add(PurchaseVoucherCreate modelToCreate)
 {
     return TaskHelper.ExecuteSync(() => AddAsync(modelToCreate));
 }