title: NotImplementedError: Can't perform this operation for unregistered loader type
body: <p>I'm making a small script to generate an HTML file. For this purpose, I'm using <code>jinja2</code>. </p>
  
  <p>This is my script (found in the <code>jinja2</code> documentation):</p>
  
  <pre><code># -*- coding: utf-8 -*-
  
  from jinja2 import Environment, PackageLoader
  
  env = Environment(loader = PackageLoader('monapplication', 'templates'))
  template = env.get_template('index.html')
  print(template.render(message = "Bienvenue sur mon site !"))
  </code></pre>
  
  <p>The package "monapplication" contains the folder "templates" where my index.html file is located.</p>
  
  <p>But when I run the script, I get this error:</p>
  
  <blockquote>
    <p>"NotImplementedError; Can't perform this operation for unregistered
    loader type."</p>
  </blockquote>
  
  <p>I did some research, but I didn't find any solution for my problem.</p>
  
  <p>My OS is Windows 10.</p>