I am working on playing with some Python to create a webapp. At first I put the HTML in a string, using %s to fill certain elements. That all worked perfectly. Now I want to put the HTML in a template, so I followed this tutorial.

My code looks like this (I deleted irrelevant code for this error):

import codecs
import cgi
import os
import jinja2

jinja_environment = jinja2.Environment(loader=jinja2.FileSystemLoader(os.path.join(os.path.dirname(__file__))))

class Rot13Handler(webapp2.RequestHandler):
    def get(self):
        template = jinja_environment.get_template('rot13.html')    
        self.response.out.write(template.render({'text': ''}))

When I replace just template.render({'text': ''}) a random string, the program works fine.
I did add the latest jinja2 library to my app.yaml, and naturally my rot13.html does exist with the {{ text }} added.

So could anyone please help me in the right direction? I don't know why it's going wrong.