raiting for CodeAcademy

from lxml import html

class User(object):
    def __init__(self, username):
        self.username = username
        
    def achievements(self):
        try:
            page = html.parse(user_achievements_url %{'username':self.username})
        except IOError:
            return []
        else:
            cards = page.xpath(achievement_card_xpath)
            return [card.text for card in cards]

    @staticmethod
    def show_raiting(usernames):
        user_achievements_url = 'http://www.codecademy.com/users/%(username)s/achievements'
        achievement_card_xpath = "//*[contains(@class, 'achievement-card')]/h5"
        
        users = [User(name) for name in usernames]
        raiting = dict([(user.username, len(user.achievements())) for user in users])

        print '# username cards'
        for i, user in enumerate(sorted(raiting)): 
            print i+1, user, raiting[user]
            
usernames = ['_nonamenix', ]
User.show_raiting(usernames)