public Task<Order> NewOrderAsync(Guid walletId, NewOrder order)
		{
			if (walletId == Guid.Empty)
				throw new ArgumentException("walletId");
			if (order == null)
				throw new ArgumentNullException("order");

			var request = new NewOrderMessageBuilder(walletId, order);
			return SendAsync(request).ReadAsAsync<Order>();
		}
 public NewOrderMessageBuilder(Guid walletId, NewOrder order)
 {
     _walletId = walletId;
     _order = order;
 }