Convert between UTC and local time without third party tz libraries

timezone.py

def utc_to_local(dt):
    """
    Converts a naive datetime from UTC to local time, returning a new naive
    datetime.
    """
    return datetime.fromtimestamp(calendar.timegm(dt.utctimetuple()))

def local_to_utc(dt):
    """
    Converts a naive datetime from local to UTC time, returning a new naive
    datetime.
    """
    return datetime.utcfromtimestamp(time_m.mktime(dt.timetuple()))