def daysLeft(self,date):
        from pandas import  DateRange # this will cause a problem with pandas 0.14 and higher... Method is depreciated and replaced by DatetimeIndex

        r = DateRange(date,self.expirationDate())
        return len(r)
business days to expiration date
dataset/ETHPy150Open sjev/trading-with-python/lib/cboe.py/VixFuture.daysLeft