Combo

combo.js

/** Write a function `combo` that takes two parameters--fn1, fn2--and returns a function. 
* combo should combine the two function parameters and invoke them on any values passed as arguments
* ex: 
* var add2 = (n) => n + 2;
* var times3 = (n) => n * 3;
* var plus2AndMultiply3 = combo(add2, times/3)
* plus2AndMulitply3(5) // --> 17
*/
// Function composition in Es6
const combo = (fn1, fn2) => (...args) => fn1(fn2(args));

// ES5
function combo (fn1, fn2) {
  return function () {
    var args = Array.prototype.slice.call(arguments);
    return fn1(fn2(args));
  }
}