code: def getValue(self):
      ret = None
      if self.windowFull():
          values = self.getValues()
          prev = values[0]
          actual = values[1]
          netReturn = (actual - prev) / float(prev)
          ret = (1 + self.__prevCumRet) * (1 + netReturn) - 1
          self.__prevCumRet = ret
      return ret
  
file_path: pyalgotrade/pyalgotrade/technical/cumret.py
imports: from pyalgotrade import technical
label_desc: Use image node_id 2 for calling the CumRetEventWindow obj's underlying member method code with example usage: obj.getValue() and returns: ret