how to get tz_info object corresponding to current timezone?

>>> import datetime
>>> today = datetime.datetime.now()
>>> insummer = datetime.datetime(2009,8,15,10,0,0)
>>> from pytz import reference
>>> localtime = reference.LocalTimezone()
>>> localtime.tzname(today)
'PST'
>>> localtime.tzname(insummer)
'PDT'
>>>