如何为嵌套的.JSON树(Python字典)调整Python代码，使其包含多个键？

def add_keys_to_json_tree(json_tree, keys):
    if isinstance(json_tree, dict):
        for key in keys:
            json_tree[key] = None
        for value in json_tree.values():
            add_keys_to_json_tree(value, keys)
    elif isinstance(json_tree, list):
        for item in json_tree:
            add_keys_to_json_tree(item, keys)

json_tree = {
    "key1": {
        "key2": {
            "key3": {
                "key4": "value4"
            }
        }
    }
}

keys_to_add = ["key5", "key6"]
add_keys_to_json_tree(json_tree, keys_to_add)

{
    "key1": {
        "key2": {
            "key3": {
                "key4": "value4",
                "key5": None,
                "key6": None
            },
            "key5": None,
            "key6": None
        },
        "key5": None,
        "key6": None
    },
    "key5": None,
    "key6": None
}