docs: def submit_form_id(self, id_):
      """
      Submit the form with given id (used to disambiguate between multiple
      forms).
      """
      form = ElementSelector(
          world.browser,
          str('id("{id}")'.format(id=id_)),
      )
      assert form, "Cannot find a form with ID '{}' on the page.".format(id_)
      form.submit()