Write a function that will flatten an array of arbitrarily nested arrays of integers into a flat array of integers. e.g. [[1,2,[3]],4] → [1,2,3,4]. If the language you're using has a function to flatten arrays, you should pretend it doesn't exist.
clone this repo
npm install
npm test
import flatten from './array-flattener'
flatten([[1,2,[3]],4])