code: def __init__(self, initialValue):
      self.__lastValue = initialValue
      self.__flows = 0.0
      self.__lastPeriodRet = 0.0
      self.__cumRet = 0.0
  
imports: import math
  from pyalgotrade import stratanalyzer
  from pyalgotrade import observer
  from pyalgotrade import dataseries
label_desc: Use image node_id 1 to create a new TimeWeightedReturns object from inherited base classes: object with example: obj = TimeWeightedReturns(initialValue)