Implementing a Python datetime localizer using python-dateutil

gistfile1.py

from dateutil import tz

def _convert_tz(val, from_tzinfo, to_tzinfo):
    # Interpret the naive datetime as in the 'from' time zone
    val = val.replace(tzinfo=from_tzinfo)

    # Convert to specified time zone
    val = val.astimezone(to_tzinfo)

    # Make it a naive datetime again
    val = val.replace(tzinfo=None)

    return val

def convert_tz(val, from_zone, to_zone):
    """Converts a naive datetime object between two Olson time zones"""
    return _convert_tz(val, tz.gettz(from_zone), tz.gettz(to_zone))

def localize(val, to_zone=None):
    """Localizes the specified datetime object from UTC to the given Olson time zone"""
    to_tzinfo = tz.gettz(to_zone) if to_zone else tz.tzlocal()
    return _convert_tz(val, tz.tzutc(), to_tzinfo)

def to_utc(val, from_zone=None):
    """Takes a naive datetime object presumed to be in the given Olson time zone and converts it to UTC."""
    from_tzinfo = tz.gettz(from_zone) if from_zone else tz.tzlocal()
    return _convert_tz(val, from_tzinfo, tz.tzutc())