如何在嵌套字典中搜索内容并修改嵌套字典？

def search_and_modify(dictionary, target_key, new_value):
    for key, value in dictionary.items():
        if key == target_key:
            dictionary[key] = new_value
        elif isinstance(value, dict):
            search_and_modify(value, target_key, new_value)

nested_dict = {
    'key1': 'value1',
    'key2': {
        'key3': 'value3',
        'key4': 'value4'
    }
}

search_and_modify(nested_dict, 'key3', 'new_value3')

print(nested_dict)

{
    'key1': 'value1',
    'key2': {
        'key3': 'new_value3',
        'key4': 'value4'
    }
}