Search key in structure by yield

structure_search.py

def is_flatted(data):
    assert isinstance(data, dict)

    def _inner(item):
        for k, v in item.items():
            print("key: %r" % k)

            if "." in k:
                yield True

            if isinstance(v, dict):
                yield from _inner(v)

    return any(i for i in _inner(data))


d1 = {
    "b": 2,
    "c": {
        "d": 3
    },
    "test": {
        "path": {
            "a": 1
        },
    },

}

d2 = {
    "test": {
        "path.test": {
            "a": 1
        },
    },
    "b": 2
}

d3 = {
    "test": {
        "path": {
            "a": 1
        },
    },
    "b": 2,
    "c": {
        "d": {
            "f.e": 3
        }
    }
}

assert not is_flatted(d1)
assert is_flatted(d2)
assert is_flatted(d3)