tornado.options.options don't parse default value automatically

gistfile1.txt

# -*- coding: utf-8 -*-
#
# Copyright (c) 2013 feilong.me All rights reserved.
#
# @author: Felinx Lee <felinx.lee@gmail.com>
# Created on May 4, 2013
#

"""
tornado.options.options don't parse default value automatically, sometimes, 
the option's value is not the same as what we expected. 

For example:

file:
test_options.py

run:
python test_options.py --addresses=127.0.0.1,192.168.1.1 --age=18

output:
default age:  10 <type 'str'>
default addresses:  127.0.0.1,192.168.1.1 <type 'str'>
parsed age:  18 <type 'int'>
parsed addresses:  ['127.0.0.1', '192.168.1.1'] <type 'list'>

"""

from tornado.options import options, define

define("age", default="10", type=int)
define("addresses", default="127.0.0.1,192.168.1.1", type=str, multiple=True)

print "default age: ", options.age, type(options.age)
print "default addresses: ", options.addresses, type(options.addresses)

options.parse_command_line()

print "parsed age: ", options.age, type(options.age)
print "parsed addresses: ", options.addresses, type(options.addresses)