code: def serve_file(self, private_file):
          
          response = self.server_class().serve(private_file)
  
          if self.content_disposition:
              # Join syntax works in all Python versions. Python 3 doesn't support b'..'.format(),
              # and % formatting was added for bytes in 3.5: https://bugs.python.org/issue3982
              filename = self.get_content_disposition_filename(private_file)
              response['Content-Disposition'] = b'; '.join([
                  self.content_disposition.encode(), self._encode_filename_header(filename)
              ])
  
          return response
docs: Serve the file that was retrieved from the storage.
          The relative path can be found with ``private_file.relative_name``.
  
          :type private_file: :class:`private_storage.models.PrivateFile`
          :rtype: django.http.HttpResponse