如果子对象为空，如何删除python3中的父json元素

import json

def delete_empty_parent(json_obj):
    if isinstance(json_obj, dict):
        for key, value in list(json_obj.items()):
            if value is None:
                del json_obj[key]
            else:
                delete_empty_parent(value)
    elif isinstance(json_obj, list):
        for item in json_obj:
            delete_empty_parent(item)

# 示例JSON字符串
json_str = '''
{
  "name": "John",
  "age": 30,
  "address": {
    "street": "123 Street",
    "city": null,
    "country": "USA"
  },
  "children": [
    {
      "name": "Alice",
      "age": 5,
      "address": null
    },
    {
      "name": "Bob",
      "age": 8,
      "address": {
        "street": null,
        "city": "New York",
        "country": "USA"
      }
    }
  ]
}
'''

# 将JSON字符串解析为Python对象
json_obj = json.loads(json_str)

# 删除父JSON元素
delete_empty_parent(json_obj)

# 将修改后的JSON对象转换回JSON字符串
modified_json_str = json.dumps(json_obj, indent=2)
print(modified_json_str)