code: def attached(self, strat):
      self.__portfolioReturns = TimeWeightedReturns(
          strat.getBroker().getEquity()
      )
  
imports: import math
  from pyalgotrade import stratanalyzer
  from pyalgotrade import observer
  from pyalgotrade import dataseries
label_desc: Use image node_id 3 for calling the ReturnsAnalyzerBase obj's underlying member method code with example usage: obj.attached(strat) without return types