examples/flask/15/app.py
from flask import Flask, jsonify
app = Flask(__name__)

@app.route("/")
def main():
    return '''
Main<br>
<a href="/user/23">23</a><br>
<a href="/user/42">42</a><br>
'''

@app.route("/user/<id>")
def api_info(id):
    return id