[FEAT] def_async

i made a simple Awaitable class in c++ to support pythons async/await syntax with c++ deferred functions:

template<typename ResultType>
class Awaitable : public std::enable_shared_from_this<Awaitable<ResultType>>{
    public:
        Awaitable();
        Awaitable(std::future<ResultType>&);
        std::shared_ptr<Awaitable<ResultType>> __iter__();
        std::shared_ptr<Awaitable<ResultType>> __await__();
        
        void __next__();

    private:
        std::future<ResultType> future;
};

is this something that would have a chance to land in pybind11?
So, supporting an interface like:

m.def_async("name", &function_returning_a_future);

What seems to be missing for this is a StopIteration exception type with templated "return" type.

The proposal centers on a C++ Awaitable class and a hypothetical m.def_async("name", &function_returning_a_future) entry point. Start by determining whether this interface belongs in pybind11 and how the proposed await/next behavior and templated StopIteration return should be scoped; done requires an agreed design and implementation plan.