/// <summary>
        /// Creates a new payment under the authenticated account. Makes a POST and a GET request to the Invoices/Payments resource.
        /// </summary>
        /// <param name="invoiceId">The Id of the invoice being paid</param>
        /// <param name="options">The options for the new payment to be created</param>
        public Payment CreatePayment(long invoiceId, PaymentOptions options)
        {
            var request = Request("invoices/" + invoiceId + "/payments", RestSharp.Method.POST);

            request.AddBody(options);

            return Execute<Payment>(request);
        }
        /// <summary>
        /// Creates a new payment under the authenticated account. Makes both a POST and a GET request to the Invoices/Payments resource.
        /// </summary>
        /// <param name="invoiceId">The Id of the invoice being paid</param>
        /// <param name="amount">The amount of the payment</param>
        /// <param name="paidAt">The the date of the payment</param>
        /// <param name="notes">Notes on the payment</param>
        public Payment CreatePayment(long invoiceId, decimal amount, DateTime paidAt, string notes = null)
        {
            var newPayment = new PaymentOptions()
            {
                Amount = amount,
                PaidAt = paidAt,
                Notes = notes
            };

            return CreatePayment(invoiceId, newPayment);
        }