Render template.

        :param context: A dict or dict-like object to instantiate given
            template file
        :param kwargs: Keyword arguments passed to the template engine to
            render templates with specific features enabled.

        :return: Rendered string

def __render(self, context, **kwargs):
        """
        Render template.

        :param context: A dict or dict-like object to instantiate given
            template file
        :param kwargs: Keyword arguments passed to the template engine to
            render templates with specific features enabled.

        :return: Rendered string
        """
        # Not pass both searchList and namespaces.
        kwargs["namespaces"] = [context, ] + kwargs.get("namespaces", []) \
                                           + kwargs.get("searchList", [])
        kwargs["searchList"] = None

        # TODO:
        # if at_paths is not None:
        #    paths = at_paths + self._engine_valid_opts.get(..., [])
        #    ...
        kwargs = self.filter_options(kwargs, self.engine_valid_options())
        self.engine_options.update(kwargs)

        return render_impl(**self.engine_options)