function digit的用法和樣例：
例句
- A function is uniquely represented by a name and a set of operand types.
函數由函數名以及一組操作數類型唯一地表示。 - Based on sign digit negabinary representation, the two step addition and one step subtraction of arbitrary length operands can be performed.
基於符號數字負二進位表達，提出了任意字長操作數的并行兩步加法與一步減法。
