Given this simplified Python Flask code snippet handling token refresh, what will be the output if the refresh token is expired?

Given this simplified Python Flask code snippet handling token refresh, what will be the output if the refresh token is expired?

from flask import Flask, request, jsonify
app = Flask(__name__)

@app.route('/refresh', methods=['POST'])
def refresh():
    token = request.json.get('refresh_token')
    if token == 'valid_token':
        return jsonify({'access_token': 'new_access_token'}), 200
    else:
        return jsonify({'error': 'Invalid or expired token'}), 401

# Simulate request with expired token
print(refresh())