Checks if value is an arrow function object.
This function is used to distinguish an arrow function from a regular function.
See http://stackoverflow.com/q/34244183/368691 for a discussion regarding the best method to determine if value is an arrow function.
import isArrowFunction from 'is-arrow-function';
isArrowFunction(() => {});
// true
isArrowFunction(function () {});
// false
npm install isarrowfunction