public Task <IReadOnlyList <BalanceModel> > GetLykkeAsync()
        {
            IReadOnlyCollection <Balance> balances = _balanceService.GetByExchange(ExchangeNames.Lykke);

            var model = Mapper.Map <BalanceModel[]>(balances);

            return(Task.FromResult <IReadOnlyList <BalanceModel> >(model));
        }
        public Task <IReadOnlyList <BalanceModel> > GetAsync(string exchange = null)
        {
            IReadOnlyList <Balance> balances;

            if (string.IsNullOrEmpty(exchange))
            {
                balances = _balanceService.GetAll();
            }
            else
            {
                balances = _balanceService.GetByExchange(exchange);
            }

            return(Task.FromResult(Mapper.Map <IReadOnlyList <BalanceModel> >(balances)));
        }