docs: function finalizeBuildOnce(config, data, callback) {
    maybeDisableMockjax();
    let options = {
      xhr: getNativeXhr,
      method: 'POST',
      // Use "async: false" to block the browser from shutting down until the finalize_build call
      // has fully returned. This prevents testem from shutting down the express server until
      // our middleware has finished uploading resources and resolving promises.
      async: false,
      timeout: 30000,
    };
    percyJQuery.ajax('/_percy/finalize_build', options)
      .done( () => {
        if(callback) {
          callback();
        }
      });
    maybeResetMockjax();
  }