def __get_timemachine(self):
        """Return a TimeMachine for the object on which this action was 
        performed and at the time of this action."""
        if not self.__timemachine:
            self.__timemachine = TimeMachine(
                self.object_uid,
                step = self.id,
            )

        return self.__timemachine.at(self.id)
def __get_timemachine ( self ) : if not self . __timemachine : self . __timemachine = TimeMachine ( self . object_uid , step = self . id , ) return self . __timemachine . at ( self . id )
Return a TimeMachine for the object on which this action was 
        performed and at the time of this action.