Python kodundaki hata nedir?

from flask import Flask, render_template, request, redirect, url_for, session
from flask_mysqldb import MySQL
import MySQLdb.cursors
import re
import pymysql


app = Flask(__name__)


app.secret_key = 'your secret key'



app.config['MYSQL_HOST'] = 'u'
app.config['MYSQL_USER'] = 'u'
app.config['MYSQL_PASSWORD'] = ''
app.config['MYSQL_DB'] = ''


mysql = MySQL(app)


@app.route('/')
@app.route('/login', methods =['GET', 'POST'])
def login():
    msg = ''
    if request.method == 'POST' and 'username' in request.form and 'password' in request.form:
        username = request.form['username']
        password = request.form['password']
        cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
        cursor.execute('SELECT * FROM accounts WHERE username = % s AND password = % s', (username, password ))
        account = cursor.fetchone()
    if account:
        session['loggedin'] = True
        session['id'] = account['id']
        session['username'] = account['username']
        msg = 'Logged in successfully !'
        return render_template('index.html', msg = msg)
    else:
        msg = 'Incorrect username / password !'
        return render_template('login.html', msg = msg)


@app.route('/logout')
def logout():
    session.pop('loggedin', None)
    session.pop('id', None)
    session.pop('username', None)
    return redirect(url_for('login'))


@app.route('/register', methods =['GET', 'POST'])
def register():
    msg = ''
    if request.method == 'POST' and 'username' in request.form and 'password' in request.form and 'email' in request.form :
        username = request.form['username']
        password = request.form['password']
        email = request.form['email']
        cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
        cursor.execute('SELECT * FROM accounts WHERE username = % s', (username, ))
        account = cursor.fetchone()
        if account:
             msg = 'Account already exists !'
        elif not re.match(r'[^@]+@[^@]+\.[^@]+', email):
            msg = 'Invalid email address !'
        elif not re.match(r'[A-Za-z0-9]+', username):
            msg = 'Username must contain only characters and numbers !'
        elif not username or not password or not email:
            msg = 'Please fill out the form !'
        else:
            cursor.execute('INSERT INTO accounts VALUES (NULL, % s, % s, % s)', (username, password, email, ))
            mysql.connection.commit()
            msg = 'You have successfully registered !'
    elif request.method == 'POST':
         msg = 'Please fill out the form !'
    return render_template('register.html', msg = msg)

if __main__ = (__main__)