[计] require variable declaration

yāo qiú zuò biàn liàng shēng míng ㄧㄠ ㄑㄧㄡˊ ㄗㄨㄛˋ ㄅㄧㄢˋ ㄌㄧㄤˋ ㄕㄥ ㄇㄧㄥˊ