luaL_opt
return luaL_opt(L, luaL_checknumber, narg, def);
return luaL_opt(L, luaL_checkinteger, narg, def);
return luaL_opt(L, luaL_checkunsigned, narg, def);
last = luaL_opt(L, luaL_checkint, 4, luaL_len(L, 1));
e = luaL_opt(L, luaL_checkint, 3, luaL_len(L, 1));