207         return True

   207         return True

   208 

   208 

   209     def __hash__(self):

   209     def __hash__(self):

   210         return id(self)

   210         return id(self)

   211 

   211 

   213         raise NotImplementedError('comparison not implemented for %s' % self.__class__)

   213         raise NotImplementedError('comparison not implemented for %s' % self.__class__)

   214 

   214 

   215     def pre_add_hook(self):

   215     def pre_add_hook(self):

   216         """hook called by the repository before doing anything to add the entity

   216         """hook called by the repository before doing anything to add the entity

   217         (before_add entity hooks have not been called yet). This give the

   217         (before_add entity hooks have not been called yet). This give the