public async Task <Dictionary <string, List <CommodityPriceData> > > GetPricesData(IEnumerable <LastPriceDateDto> lastPricesData, string baseCurrency)
        {
            var data = await _client.GetHistoricNbpCurrenciesData();

            var result = new Dictionary <string, List <CommodityPriceData> >();

            foreach (var keyValuePair in data.Data)
            {
                result.Add(keyValuePair.Key, keyValuePair.Value.Select(q => new CommodityPriceData()
                {
                    Date     = q.Date,
                    Mnemonic = q.Currency,
                    Price    = q.Price
                }).ToList());
            }

            return(result);
        }