old_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals, absolute_import
  
  
  class HarvestException(Exception):
      '''Base class for all harvest exception'''
      pass
  
  
  class HarvestSkipException(HarvestException):
      '''Raised when an item is skipped'''
      pass
  
new_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals, absolute_import
  
  
  class HarvestException(Exception):
      '''Base class for all harvest exception'''
      pass
  
  
  class HarvestSkipException(HarvestException):
      '''Raised when an item is skipped'''
      pass
  
  
  class HarvestValidationError(HarvestException):
      '''Raised when an harvested item is invalid'''
      pass
  
subject: Introduce HarvestValidationError