python 怎么判断一个时间是否过期

>>> import datetime
>>> datetime.datetime.now()

from datetime import datetime
datetime_from_db='2015-10-26 00:00:00'
datetime_of_datetime_from_db=datetime.strptime(datetime_from_db,'%Y-%m-%d %H:%M:%S')
delta_time=datetime.now()-datetime_of_datetime_from_db
if delta_time.days<0:
print('expired')
else:
print('valid')

注意一下时区是否相同，如果相同就简单了：

```python
import datetime

def is_expired(dt):
if isinstance(dt, str):
dt = datetime.datetime.strptime(dt, '%Y-%m-%d %H:%M:%S')
return datetime.datetime.now() > dt
```

>>> is_expired('2015-10-26 00:00:00')
True

>>> is_expired('2015-11-26 00:00:00')
False