def METHOD_NAME() -> None:
    l = {"a": {"b": 1, "d": 2}, "d": 2, "e": 4}
    r = {"a": {"c": 1, "d": 3}, "d": 1}
    assert deep_merge(l, r) == {"a": {"b": 1, "c": 1, "d": 3}, "d": 1, "e": 4}
    a = {"a": {"foo": {"first": "first", "last": "laaaast"}}, "b": {"bar": 123}, "c": [6, 7]}
    b = {"a": {"foo": {"last": "last"}}, "b": {"baz": 456}, "c": [8, 9]}
    assert deep_merge(a, b) == {
        "a": {"foo": {"first": "first", "last": "last"}},
        "b": {"bar": 123, "baz": 456},
        "c": [8, 9],
    }