in src/annoygomodule.h [109:119]
void getNnsByItem(int item, int n, int search_k, AnnoyVectorInt* out_result, AnnoyVectorFloat* out_distances) {
vector<int32_t>* result = new vector<int32_t>();
vector<float>* distances = new vector<float>();
ptr->get_nns_by_item(item, n, search_k, result, distances);
out_result->fill_from_vector(result);
out_distances->fill_from_vector(distances);
delete result;
delete distances;
};