Transform dot-notation keys into nested dictionary

dot2dict.py

def dot2dict(a):
    dict_tree = lambda: defaultdict(dict_tree)
    output = dict_tree()
    for k, v in a.items():
        path = k.split(".")
        target = reduce(lambda d, k: d[k], path[:-1], output)
        target[path[-1]] = v
    return output


if __name__ == "__main__":
    print(
        dot2dict(
            {
                "event.name": "progress",
                "event.status": "complete",
                "event.user.name": "bob",
                "event.user.email": "bob@gmail.com",
            }
        )
    )