template_dir = os.path.join(os.path.dirname(__file__), 'views')
env = jinja2.Environment(
    loader=jinja2.FileSystemLoader(template_dir),
    autoescape=True)

self.render('some_template.html', env=env)   # render function

app/
  shared/
    header.html <-- templates within modules need to access these
    nav.html
  modules/
    module_a/
      handler.py
      templates/
        my_template.html  <-- needs access to partials from 'shared/'
    module_b/
    module_c/