Added comments to remove Engine.render_to_string in Django 2.0.

            template = Template(template, origin, template_name, engine=self)

        return template

    # This method was originally a function defined in django.template.loader.

    # It was moved here in Django 1.8 when encapsulating the Django template

    # engine in this Engine class. It's still called by deprecated code but it

    # will be removed in Django 2.0. It's superseded by a new render_to_string

    # function in django.template.loader.

    def render_to_string(self, template_name, context=None,

                         context_instance=_context_instance_undefined,

                         dirs=_dirs_undefined,

                         dictionary=_dictionary_undefined):

        """

        Loads the given template_name and renders it with the given dictionary as

        context. The template_name may be a string to load a single template using

        get_template, or it may be a tuple to use select_template to find one of

        the templates in the list. Returns a string.

        """

        if context_instance is _context_instance_undefined:

            context_instance = None

        else:

        # Some deprecated arguments were passed - use the legacy code path

        for engine in _engine_list(using):

            try:

                # This is required for deprecating arguments specific to Django

                # templates. Simply return engine.render_to_string(template_name,

                # context) in Django 2.0.

                # This is required for deprecating properly arguments specific

                # to Django templates. Remove Engine.render_to_string() at the

                # same time as this code path in Django 2.0.

                if isinstance(engine, DjangoTemplates):

                    # Hack -- use the internal Engine instance of DjangoTemplates.

                    return engine.engine.render_to_string(