code: public static BitfinexTickerSymbol ticker(final String currency, final String profitCurrency) {
      	
          final String currencyNonNull = Objects.requireNonNull(currency).toUpperCase();
          final String profitCurrencyNonNull = Objects.requireNonNull(profitCurrency).toUpperCase();
          
          return ticker(BitfinexCurrencyPair.of(currencyNonNull, profitCurrencyNonNull));
      }
docs: returns symbol for ticker channel
  
  @param currency       of ticker
  @param profitCurrency of ticker
  @return symbol