如何在可能包含更多列表或多个字典列表的嵌套字典中查找子字符串的所有实例

def find_substring_in_nested_dict(nested_dict, substring):
    instances = []

    def search_dict(dictionary, substring):
        for key, value in dictionary.items():
            if isinstance(value, dict):
                search_dict(value, substring)
            elif isinstance(value, list):
                for item in value:
                    if isinstance(item, dict):
                        search_dict(item, substring)
                    elif isinstance(item, str) and substring in item:
                        instances.append(item)
            elif isinstance(value, str) and substring in value:
                instances.append(value)

    search_dict(nested_dict, substring)
    return instances

nested_dict = {
    'key1': 'value1',
    'key2': {
        'key3': 'value2',
        'key4': [
            'value3',
            'value4',
            {
                'key5': 'value5',
                'key6': 'value6'
            }
        ]
    }
}

substring = 'value'
instances = find_substring_in_nested_dict(nested_dict, substring)
print(instances)

['value1', 'value2', 'value3', 'value4', 'value5', 'value6']