How can I access html page through flask app and then another html page from the same flask app

@app.route('/'):
def index():
   return render_template("index.html")

Register

@app.route('/register')
def register():
   # Ensure the user reached path via GET
   if request.method == "GET":
      return render_template("another_file.html")

   else:
      pass # Pass is a Python way to say 'do nothing'