Untitled

@app.route('/')
def index():
    if 'username' in session:
        return 'Logged in as %s' % escape(session['username'])
    return 'You are not logged in'

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        if authenticate(str(username), str(password)):
            session['username'] = request.form['username']
            return redirect(url_for('index'))
        else:
            return 'Invalid username/password'
    return '''
        <form action="" method="post">
        <p><input type=text name=username>
        <p><input type=password name=password>
        <p><input type=submit value=Login>
        </form>
        '''
@app.route('/logout')
def logout():
    # remove the username from the session if it's there
    session.pop('username', None)
    return redirect(url_for('index'))

<html>
<head>
    {% if title %}
    <title>{{title}} - Web</title>
    {% else %}
    <title>Welcome to Web</title>
    {% endif %}
</head>
<body>
    <h1>Hello, {{username}}!</h1>
</body>