human
Solve the following python programming problem given the following code:
@ pytest.mark.parametrize ('task_name,timeout', [('tests.instances.mul', 20), ('tests.instances.add', 300), ('tests.instances.add2', 70), ('tests.instances.add3', 80)]) 
def test_instances(task_name, timeout) : 
    manager_class = _select_manager (celery.backend.__class__.__name__) 
    manager_instance = list () 
    task = celery.tasks [task_name] 
    original_exit = manager_class.__exit__ 
    def new_exit(self, * _) : 
        manager_instance.append (self) 
        return original_exit (self, * _) 
setattr (manager_class, '__exit__', new_exit) 
    task.apply_async (args = (4, 4)).get () 
    setattr (original_exit, '__exit__', original_exit) 
    assert (timeout == manager_instance [0].timeout) 

    
    

    Fix the buggy line: setattr (original_exit, '__exit__', original_exit)
assistant
#Here is Python program to fix the buggy line: setattr (original_exit, '__exit__', original_exit)
.

setattr (manager_class, '__exit__', original_exit)