如何根据键值比较两个对象？

def compare_objects(obj1, obj2, key):
    if key in obj1 and key in obj2:
        value1 = obj1[key]
        value2 = obj2[key]
        if value1 == value2:
            return "两个对象在键 {} 上的值相等".format(key)
        else:
            return "两个对象在键 {} 上的值不相等".format(key)
    else:
        return "键 {} 在至少一个对象中不存在".format(key)

# 示例对象
obj1 = {"name": "John", "age": 25, "city": "New York"}
obj2 = {"name": "John", "age": 30, "city": "New York"}

# 比较键 "age" 的值
result = compare_objects(obj1, obj2, "age")
print(result)