new_contents: from flask import Flask, render_template, request
  app = Flask(__name__)
  
  @app.route('/')
  @app.route('/index')
  def index():
      client = request.headers.get('User-Agent')
      return render_template("index.html",
          title = 'Home',
          client = client)
          
  if __name__ == '__main__':
      app.run()
  
subject: Create app.py