I am trying to access the previous period SMA indicator values. As an example, I want to get the value of the SMA(10 period) 5 bars in the past. What is the correct syntax for accessing the previous SMA indicator values?

I can access the bar data with 'self.Data[symbol].Bars[0].Low', where the '0' of 'Bars[0]' is the most recent and '1' is the previous bar data etc.
Low is the low of the bar.  I can also access the Time, High, Open and Close for each bar.
I have not been able to determine how to access the previous data for the SMA indicator. I can access the current value with 'self.Data[symbol].SMA.Current.Value' but I am not sure of how to access the previous data.  I have tried 'self.Data[symbol].SMA[1]' and I get 'unindexable object' error.
My question is what do I need to do to access the previous value of the SMA indicator?

I have attached the backtest of the algorithm.
You can see the self.Debug() statement at the end of the OnData(self,data) section.

I appreciate the help.