text: module.exports = (req, res, next) => {
    // Fastly provides a Soft Purge feature that allows you to mark content as outdated (stale) instead of permanently
    // purging and thereby deleting it from Fastly's caches. Objects invalidated with Soft Purge will be treated as
    // outdated (stale) while Fastly fetches a new version from origin.
    //
    // Use of a surrogate key is required for soft purging
    // https://docs.fastly.com/en/guides/soft-purges
    // https://docs.fastly.com/en/guides/getting-started-with-surrogate-keys
    res.set('surrogate-key', 'all-the-things')
  
    return next()
  }
  