luaL_optint
int ex = luaL_optint(L, 2, 0);
int level = luaL_optint(L, 2, 1);
int w = luaL_optint(L, farg + 1, 1);
i = luaL_optint(L, 2, 1);
int pos = luaL_optint(L, 2, size);
i = luaL_optint(L, 3, 1);