def all(self, cache=False):
        """
        can use cache to return objects
        """
        if cache:
            return [get_object(self.modelb, obj_id, cache=True, use_local=True) for obj_id in self.keys(True)]
        else:
            return self
def all ( self , cache = False ) : if cache : return [ get_object ( self . modelb , obj_id , cache = True , use_local = True ) for obj_id in self . keys ( True ) ] else : return self
can use cache to return objects