[github地址：https://github.com/ABCDdouyae…]
pad
給字串的左右加padding,也可以用於刪減字串兩端
用法：pad(str, length, options)|pad(length, str, options)
options:
- char (string)： 指定字元填充
- colors (boolean)：Ajust to hidden terminal color characters, you may also use require `pad/lib/colors` to avoid passing this option.
- strip (boolean)：要求的長度小於原字串長度，會對原字串刪減，預設false
- fixed_width (boolean)：An optimization option to disable the usage of the wcwdith package to handle the discovery of characters using more than one column for display. one column to display
- wcwidth_options (object)：Options passed to the wcwidth package used to calculate the display width of characters using more than one column.
返回：string