def SelfReferenceProperty(verbose_name=None, collection_name=None, **attrs):
 if ('reference_class' in attrs):
  raise ConfigurationError('Do not provide reference_class to self-reference.')
 return ReferenceProperty(_SELF_REFERENCE, verbose_name, collection_name, **attrs)

def SelfReferenceProperty ( verbose_name = None , collection_name = None , ** attrs ) : if ( 'reference_class' in attrs ) : raise ConfigurationError ( 'Do not provide reference_class to self-reference.' ) return ReferenceProperty ( _SELF_REFERENCE , verbose_name , collection_name , ** attrs )
create a self reference .