I am trying to implement a Rolling Window within the SymbolData class for an ensemble of SMA's. 

Essentially each security will have a RollingWindow dict to store the results of the various lookback windows - and it is using a Dict with a RollingWindow that is causing my troubles. The error I am receiving is…

During the algorithm initialization, the following exception has occurred: AttributeError : 'dict' object has no attribute 'Add'
  at SmaUpdated
    self.smaWindow.Add(updated)
  File "main.py" in main.py:line 43
 AttributeError : 'dict' object has no attribute 'Add'

And the class is below. Any help would be greatly appreciated!

class SymbolData:
    
    def __init__(self, symbol, algorithm):
        self.algorithm = algorithm
        self.Symbol = symbol
        self.sma = {}
        self.smaWindow = {}

        
        
        # Build an "Ensemble" of Moving averages
        self.sma = algorithm.SMA(self.Symbol, 9*21, Resolution.Daily)
        self.smaWindow = RollingWindow[IndicatorDataPoint](2)   
        self.sma.Updated += self.SmaUpdated
            
    def SmaUpdated(self, sender, updated):
        '''Event holder to update the fast SMA Rolling Window values'''
        self.smaWindow.Add(updated)

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