def METHOD_NAME():
    data = {
        "fish_facts": {
            "sharks": "Most will drown if they stop moving",
            "skates": "More than 200 species",
        },
        "fruits": ["apple", "peach", "watermelon"],
        "number": 52,
    }
    expected = {
        "fish_facts-sharks": "Most will drown if they stop moving",
        "fish_facts-skates": "More than 200 species",
        "fruits-0": "apple",
        "fruits-1": "peach",
        "fruits-2": "watermelon",
        "number": 52,
    }
    returned = py3.flatten_dict(data, delimiter="-")
    print("returned data")
    print(pformat(returned))
    assert returned == expected