private CategoryMonthKey GetCategoryMonthKey(TransactionSnapshot transaction, SubTransactionSnapshot subTransaction)
        {
            if (subTransaction.Category == null)
            {
                return(null);
            }

            return(new CategoryMonthKey(subTransaction.Category, transaction.TransactionDate));
        }
 private decimal GetTransactionAmount(SubTransactionSnapshot snapshot)
 {
     return(CurrencyConverter.ToDecimalValue(snapshot.Amount, snapshot.Amount_Denominator));
 }