Flatten an array of nested arrays into a single flat array. Accepts an optional depth.
npm install array-flatten --save
```javascript var flatten = require('array-flatten')
flatten([1, [2, [3, [4, [5], 6], 7], 8], 9]) //=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
flatten([1, [2, [3, [4, [5], 6], 7], 8], 9], 2) //=> [1, 2, 3, [4, [5], 6], 7, 8, 9]
(function () { flatten(arguments) //=> [1, 2, 3] })(1, [2, 3]) ```
MIT