struct Iterator{
    Boolean(*next) (Iterator* iterator, Any* key, Any* value);

    alignas(std::max_align_t)
    uint8_t payload[4 * 8];
};

struct DynamicIterator{
    Dynamic* object;
    Dynamic::map_t::iterator it;
};

Boolean Dynamic::iterate(Dynamic* dyn, Iterator* iterator){
    DynamicIterator* iter = (DynamicIterator*)iterator->payload;
    new(&iter->it)Dynamic::map_t::iterator(std::move(dyn->map.begin()));
    iter->object = dyn;
    iterator->next = [](Iterator* iterator, Any* key, Any* value) -> Boolean{
        DynamicIterator* iter = (DynamicIterator*)iterator->payload;
        if ( iter->it == iter->object->map.end() ){
            std::destroy_at(&iter->it); // if it was the last iteration, destroy it
            return false;
        }
        *key = iter->it->first;
        *value = iter->it->second;
        iter->it++;
        return true;
    };
    return true;
}


// somewhere in the user code...

Any object = ...; // <- iterable object
Iterator iter;
Any key;
Any value;

any_iter(object, &iter); // any iterator does dynamic dispatch and eventually invokes Dynamic::iterate

while ( iter.next(&iter, &key, &value) ){
    // do something
    if ( something ){
        return; // this leaves without destroying std::map::iterator inside Iterator
    }
}