code: def iiif_image_handler(prefix=None, identifier=None,
                         path=None, config=None, klass=None, auth=None, **args):
      
      if (not auth or degraded_request(identifier) or auth.image_authz()):
          # serve image
          if (auth):
              logging.debug("Authorized for image %s" % identifier)
          i = IIIFHandler(prefix, identifier, config, klass, auth)
          try:
              return i.image_request_response(path)
          except IIIFError as e:
              return i.error_response(e)
      else:
          # redirect to degraded (for not authz and for authn but not authz too)
          degraded_uri = host_port_prefix(
              config.host, config.port, prefix) + '/' + identifier + '-deg/' + path
          logging.info("Redirection to degraded: %s" % degraded_uri)
          response = redirect(degraded_uri)
          response.headers['Access-control-allow-origin'] = '*'
          return response
docs: Handler for IIIF Image Requests.
  
      Behaviour for case of a non-authn or non-authz case is to
      return 403.