Iterate over list of languages.

def iter_languages(self):
        """Iterate over list of languages."""
        default_lang = self.babel.default_locale.language
        default_title = self.babel.default_locale.get_display_name(
            default_lang)

        yield (default_lang, default_title)

        for l, title in current_app.config.get('I18N_LANGUAGES', []):
            yield l, title