old_contents: import os
  from flask import Flask
  app = Flask(__name__)
  
  @app.route("/")
  def homepage():
  	return "Hello World!"
  
  if __name__ == "__main__":
  	port = int(os.environ.get("PORT", 5000))
  	app.run(host='0.0.0.0', port=port)
  	app.run(debug=True)
new_contents: import os
  from flask import Flask
  app = Flask(__name__)
  
  @app.route("/")
  def homepage():
  	return render_template("index.html")
  
  if __name__ == "__main__":
  	port = int(os.environ.get("PORT", 5000))
  	app.run(host='0.0.0.0', port=port)
  	app.run(debug=True)
subject: Add HTML Template