Dead simple Flask OpenID app

from os.path import dirname, join
from flask import Flask, g, redirect, session
import sqlite3dbm # Simple sqlite3 key-value store written by a coworker
from flask_openid import OpenID

app = Flask("my Google OpenID app")
app.secret_key = YOUR RANDOM STRING HERE
oid = OpenID(app, join(dirname(__file__), 'openid_store'))

def open_db():
    g.db = getattr(g, 'db', None) or sqlite3dbm.sshelve.open("database.sqlite3")

def get_user():
    open_db()
    return g.db.get('oid-' + session.get('openid', ''))

@app.before_request
def set_user_if_logged_in():
    open_db() # just to be explicit ...
    g.user = get_user()

@app.route("/login")
@oid.loginhandler
def login():
    if g.user is not None:
        return redirect(oid.get_next_url())
    else:
        return oid.try_login("https://www.google.com/accounts/o8/id",
            ask_for=['email', 'fullname', 'nickname'])

@oid.after_login
def new_user(resp):
    session['openid'] = resp.identity_url
    if get_user() is None:
        user_id = g.db.get('user-count', 0)
        g.db['user-count'] = user_id + 1
        g.db['oid-' + session['openid']] = {
            'id': user_id,
            'email': resp.email,
            'fullname': resp.fullname,
            'nickname': resp.nickname}
    return redirect(oid.get_next_url())

@app.route('/logout')
def logout():
    session.pop('openid', None)
    return redirect(oid.get_next_url())

@app.route('/')
def hello():
    if g.user:
        return "hi user %(id)d (email %(email)s). <a href='/logout'>logout</a>" %(g.user)
    else:
        return "not logged in. <a href='/login'>login</a>"

if __name__ == "__main__":
    app.run(port=2664, debug=True)