docs: def render_template(self, source, **kwargs_context):
          r"""Render a template string using sandboxed environment.
  
          :param source: A string containing the page source.
          :param \*\*kwargs_context: The context associated with the page.
          :returns: The rendered template.
          """
          return self.jinja_env.from_string(source).render(kwargs_context)