How can I make var a = add(2)(3); //5 work?

Question

I want to make this syntax possible:

var a = add(2)(3); //5

based on what I read at http://dmitry.baranovskiy.com/post/31797647

I\

Answer 1

function add(a, b){
 return a && b ? a+b : function(c){return a+c;}
}

console.log(add(2, 3));
console.log(add(2)(3));