in src/annoyluamodule.cc [213:221]
static int get_nns_by_vector(lua_State* L) {
Searcher s(L);
std::vector<AnnoyT> _vec(s.self->get_f());
AnnoyT* vec = &(_vec[0]);
toVector(L, 2, s.self->get_f(), vec);
s.self->get_nns_by_vector(vec, s.n, s.search_k, &s.result,
s.include_distances ? &s.distances : NULL);
return s.pushResults(L);
}