Cast the given value to an array.
/**
* Cast the given value to an array.
*
* Source: https://github.com/jonschlinkert/class-utils/blob/master/index.js
*
* ```js
* arrayify('foo');
* //=> ['foo']
*
* arrayify(['foo']);
* //=> ['foo']
* ```
*
* @param {String|Array} `val`
* @return {Array}
*/
function arrayify(val) {
return val ? (Array.isArray(val) ? val : [val]) : [];
}