Redirecting an old URL to a new one with Flask micro-framework

from flask import Flask, redirect, url_for

app = Flask(__name__)

@app.route('/old_url')
def old_url():
    return redirect(url_for('new_url'))

@app.route('/new_url')
def new_url():
    return 'This is the new URL'

if __name__ == '__main__':
    app.run(debug=True)