Write a function named 'Once' which accept another function 'sum' ( function sum(a,b){return a+b;}) and return a function and when this returned function called, it should return result of 'sum' (i.e a+b ) passed to 'Once' function. And every time it should return same result that got at first call .
Sigiloso
var Once = function(sum){ let result ; return function (...args){ if(result) return result; result = sum(...args); return result; } }