313         return True

   313         return True

   314 

   314 

   315     def __hash__(self):

   315     def __hash__(self):

   316         return id(self)

   316         return id(self)

   317 

   317 

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

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

   320 

   320 

   321     def pre_add_hook(self):

   321     def pre_add_hook(self):

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

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

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

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