/*

Description:

We want to create a function that will add numbers together when called in succession.

add(1)(2);
// returns 3
We also want to be able to continue to add numbers to our chain.

add(1)(2)(3); // 6
add(1)(2)(3)(4); // 10
add(1)(2)(3)(4)(5); // 15
and so on.

A single call should return the number passed in.

add(1) // 1
We should be able to store the returned values and reuse them.

var addTwo = add(2);
addTwo // 2
addTwo + 5 // 7
addTwo(3) // 5
addTwo(3)(5) // 10
We can assume any number being passed in will be valid javascript number.

*/

function add(n){
  var func = function(x) {
    return add(n + x);
  };
  func.valueOf = function() {
    return n;
  };
  return func;
}
console.log(add(1)(2)(5));