code: def add_no_cache_headers(func):
      
  
      @wraps(func)
      def _dec(*args, **kwargs):
          response = func(*args, **kwargs)
          response['Expires'] = 'Thu, 01 Jan 1970 00:00:00 GMT'  # HTTP 1.0 proxies
          response['Cache-Control'] = 'max-age=0, no-cache, must-revalidate, proxy-revalidate'  # HTTP 1.1
          return response
  
      return _dec
docs: Makes sure the retrieved file is not cached on disk, or cached by proxy servers in between.
      This would circumvent any checking whether the user may even access the file.