如何在不丢失任何值的情况下反序列化具有重复键的JSON？

import json

def deserialize_json_with_duplicate_keys(json_str):
    json_obj = json.loads(json_str)
    result = {}
    
    for key, value in json_obj.items():
        if key in result:
            if isinstance(result[key], list):
                result[key].append(value)
            else:
                result[key] = [result[key], value]
        else:
            result[key] = value
    
    return result

# 示例用法
json_str = '{"key1": "value1", "key2": "value2", "key1": "value3"}'
result = deserialize_json_with_duplicate_keys(json_str)
print(result)

{'key1': ['value1', 'value3'], 'key2': 'value2'}