in src/annoyluamodule.cc [139:150]
static int save(lua_State* L) {
int nargs = lua_gettop(L);
Impl* self = getAnnoy(L, 1);
const char* filename = luaL_checkstring(L, 2);
bool prefault = true;
if (nargs >= 3) {
prefault = lua_toboolean(L, 3);
}
self->save(filename, prefault);
lua_pushboolean(L, true);
return 1;
}