docs: def _urls_for_js(urls=None):
      """
      Return templated URLs prepared for javascript.
      """
      if urls is None:
          # prevent circular import
          from .urls import urlpatterns
          urls = [url.name for url in urlpatterns if getattr(url, 'name', None)]
      urls = dict(zip(urls, [get_uri_template(url) for url in urls]))
      urls.update(getattr(settings, 'LEAFLET_STORAGE_EXTRA_URLS', {}))
      return urls