Gmail feed parser in Python

#! /usr/bin/env python

"""
Checks Gmail for unread mails by parsing the unread mail feed.
Requires python-feedparser. Set _USER and _PASSWD before using.
"""

import urllib
import feedparser

_URL = 'https://mail.google.com/mail/feed/atom/'   # Gmail feed url
_USER = ''                           # Username
_PASSWD = ''       # Password

# Colors
_GREEN = '\033[1;32m'
_YELLOW = '\033[1;33m'
_RESET = '\033[0;0m'

class GmailOpener(urllib.FancyURLopener):
    """
    Child class of urllib.FancyURLopener. Overrides the default
    prompt_user_passwd() method and returns (_USER, _PASSWD) instead.
    """

    def prompt_user_passwd(self, host, realm):
        return _USER, _PASSWD

def readMail():
    """
    Function to authenticate and read mail.
    """

    opener = GmailOpener()
    f = opener.open(_URL)

    feed = feedparser.parse(f)
    unread = feed['feed']['fullcount']

    print ('You have' + _GREEN + ' (' + _YELLOW + unread + _GREEN + ') ' +
             _RESET + 'unread mails.\n')

    if unread != '0':
        for mail in feed.entries:
            print '* ' + mail.author + ' : ' + mail.title + '\n'

if __name__ == '__main__':
    readMail()