class_docstr: A :class:`pyalgotrade.stratanalyzer.StrategyAnalyzer` that calculates
  Sharpe ratio for the whole portfolio.
  
  :param useDailyReturns: True if daily returns should be used instead of the returns for each bar.
  :type useDailyReturns: boolean.
code: def getReturns(self):
      return self.__returns
  
file_path: pyalgotrade/pyalgotrade/stratanalyzer/sharpe.py
imports: from pyalgotrade import stratanalyzer
  from pyalgotrade.stratanalyzer import returns
  from pyalgotrade.utils import stats
  import math
label_desc: Use image node_id 2 for calling the SharpeRatio obj's underlying member method code with example usage: obj.getReturns() and returns: self