new window.EmbeddedSandbox({
  target: '#sandbox',
  initialEndpoint: window.location.href,
  initialState: {
    sharedHeaders: {
      'X-SpecialHeader': 'WILL_BE_REPLACED_AUTOMATICALLY'
    }
  },
  modifyHeaders: async (url, headers) => {
    // Add Authorization header if not provided
    if (!headers.Authorization) {
      const accessToken = await window.getAccessToken();
      headers.Authorization = 'Bearer ' + accessToken;
    }
    // Modify special header if shared header is not unchecked
    if (headers['X-SpecialHeader'] === 'WILL_BE_REPLACED_AUTOMATICALLY') {
      const special = await window.getTheValue();
      headers['X-SpecialHeader'] = special;
    }
    return headers;
  }
});