@typecheck_method(key=IR, agg_ir=IR)
def copy(self, key, agg_ir):
    new_instance = self.__class__
    return new_instance(key, agg_ir)
@typecheck_method(key=IR, agg_ir=IR)
def copy(self, key, agg_ir):
    new_instance = self.__class__
    return new_instance(key, agg_ir)