public async Task <ActionResult <string> > Get()
        {
            IEnumerable <RatesDTO> rates = null;

            try
            {
                rates = await _ratesService.GetAsync();

                return(JsonConvert.SerializeObject(rates));
            }
            catch (Exception err)
            {
                _logger?.LogError("Rates controller exception: " + err.Message);

                return(null);
            }
        }