Supertrend Multisymbol

Hi,
does anyone have an idea how i can set the right data to the Supertrend indicator in a multisymbol scenario?

for example on a RelativeStrengthIndex i can do something like this:
     _rsi = _bot.Indicators.RelativeStrengthIndex(_bars.ClosePrices, 7);
Supertrend however does not have a method that takes these arguments. So my question is if there is a workaround?

Example code:
namespace cAlgo.Robots
{
   [Robot(AccessRights = AccessRights.None)]
   public class bot: Robot
   {
       List<string> _symbols = new List<string> {
           "EURUSD", “EURAUD”
       };

       List<SuperTrend> _superTrends = new List<SuperTrend>();

       protected override void OnStart()
       {

           foreach (var sym in _symbols)
           {
               SuperTrend superTrend = new SuperTrend(this, sym);
               _superTrends.Add(superTrend);
           }
       }
   }

  public class SuperTrend
    {
       Robot _bot;
       string _symbolString;
       private Symbol _symbol;
       private Bars _bars;

       private Supertrend _supertrend;
       private RelativeStrengthIndex _rsi;

       public SuperTrend(Robot bot, string symbolString)
       {
           _bot = bot;
           _symbolString = symbolString;
           _symbol = _bot.Symbols.GetSymbol(_symbolString);

           _bars = _bot.MarketData.GetBars(_bot.TimeFrame, _symbolString);

           _supertrend = _bot.Indicators.Supertrend(20, 6);
           _rsi = _bot.Indicators.RelativeStrengthIndex(_bars.ClosePrices, 7);
       }