code: def selenol_params(**kwargs):
      
      def params_decorator(func):
          """Param decorator.
  
          :param f: Function to decorate, typically on_request.
          """
          def service_function_wrapper(service, message):
              """Wrap function call.
  
              :param service: SelenolService object.
              :param message: SelenolMessage request.
              """
              params = {k: f(service, message) for k, f in kwargs.items()}
              return func(service, **params)
          return service_function_wrapper
      return params_decorator
docs: Decorate request parameters to transform them into Selenol objects.