npm i @a0znpm/feutils -D

 // no tree-saking ？？？ TODO
 import {luhnCheck} from '@a0nznpm/feutils'
 luhnCheck()

 import luhnCheck from '@a0nznpm/feutils/src/luhnCheck'
 luhnCheck()

 // no tree-saking ？？？ TODO
 const {luhnCheck} = '@a0nznpm/feutils'
 luhnCheck()