new_contents: # -*- coding: utf-8 -*-
  
  
  class ErrorDesctiptorEvent(object):
      """ Error descriptor event.
          'params' attribute can be extended with extra records by event handler.
      """
  
      def __init__(self, errors, params):
          self.errors = errors
          self.params = params
          self.request = errors.request
  
subject: define error descriptor event