Python trouble converting milliseconds to datetime and back -

so have 2 functions converting python datetime.datetime() objects , milliseconds. cannot figure out going wrong. here's i'm working with:

>>> import datetime >>> def mil_to_date(mil):     """date items rest services reported in milliseconds,     function convert milliseconds datetime objects      required:         mil -- time in milliseconds     """     if mil == none:         return none     elif mil < 0:         return datetime.datetime.utcfromtimestamp(0) + datetime.timedelta(seconds=(mil/1000))     else:         return datetime.datetime.fromtimestamp(mil / 1000)  >>> def date_to_mil(date):     """converts datetime.datetime() object milliseconds      date -- datetime.datetime() object"""     if isinstance(date, datetime.datetime):         epoch = datetime.datetime.utcfromtimestamp(0)         return long((date - epoch).total_seconds() * 1000.0)  >>> mil = 1394462888000 >>> date = mil_to_date(mil) >>> date datetime.datetime(2014, 3, 10, 9, 48, 8)  #this correct >>> d2m = date_to_mil(date) >>> d2m 1394444888000l >>> mil 1394462888000l >>> date2 = mil_to_date(d2m) >>> date2 datetime.datetime(2014, 3, 10, 4, 48, 8) #why did lose 5 hours?? 

for reason, losing 5 hours. overlooking obvious? or there problem 1 or both of functions?

the reason date_to_mil works utc , mil_to_date doesn't. should replace utcfromtimestamp fromtimestamp.

further explanation:

in code, epoch date of epoch in utc (but object without time-zone). date local since fromtimestamp returns local time:

if optional argument tz none or not specified, timestamp converted platform’s local date , time, , returned datetime object naive

so subtract utc epoch local datetime , delay local delay utc.