function zfilter is not usable for datetime type

1048         for i in self.db.zrange(self.key, 0, -1):
1049             print i, self.db.zscore(self.key, i)
1050         print self.key, min, max
1051         return self.db.zrangebyscore(self.key, min, max, **kwargs)

The key  and the score:
    1471795200.000000 1.0
    1471536000.000000 2.0
The min and max for float datetime:
    BBSRecord:post_date 1471708800.0 1472313599.0
