Function lua_dup

library/include/LuaWrapper.h:116–116

    constexpr auto UPVAL_ITEM_COUNT = lua_upvalueindex(6);

    inline void lua_dup(lua_State *state) { lua_pushvalue(state, -1); }
    inline void lua_swap(lua_State *state) { lua_insert(state, -2); }

    /**