How to save a dictionary and a list in the same json file with python?

I wish to save a dictionary and a list in one json file so that when I parse the file I could distinguish them.
This is the function I use to save the dictionary in the json file:

def save_callback():
    #folder = filedialog.askdirectory()
    file = filedialog.asksaveasfilename()
    with open(file,'w') as file:
        file.write(json.dumps(test_dict))
    os.rename(file.name,file.name + ".txt")

What should I add to this function to save the list too?

>Solution :

Since JSON objects can be arbitrarily nested, the easiest solution is to store both the dict and the list inside another object:

data = json.dumps([test_dict, test_list])

Then you can load it like this:

test_dict, test_list = json.loads(data)