def _missingDates(self):
        ''' check for missing dates based on spy data'''
        print 'Getting yahoo data to determine business dates... ',
        spy = yf.getHistoricData('SPY',sDate = (2010,1,1))
        busDates = [d.date() for d in spy.index ]

        print 'Date range: ', busDates[0] ,'-', busDates[-1]
        missing = []
        for d in busDates:
            if self.dates not in d:
                missing.append(d)

        return missing
dataset/ETHPy150Open sjev/trading-with-python/lib/bats.py/BATS_Data._missingDates/swapped operands of `not in`