```python >>> rapidjson.dumps({1}, iterable_mode=rapidjson.IM_ANY_ITERABLE) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: {1} is not JSON serializable ``` ```python >>> rapidjson.__version__ '1.8' ``` Given that documentation states "any iterable will be dumped as a JSON array," I would expect a set object to serialize to an array. Note, it does appear that creating an iterator object from the set will successfully serialize: ```python >>> rapidjson.dumps(iter({1}), iterable_mode=rapidjson.IM_ANY_ITERABLE) '[1]' ```