// Given a function fn, return a new function that is identical

// to the original function except that it ensures fn is called at most once.

/**

* @param {Function} fn

* @return {Function}

*/

const once = function(fn) {

let functionCalled = false;

let result;

return function(...args){

if(!functionCalled){

result = fn(...args)

functionCalled = true

return result;

}else {

return undefined;

}

}

};

/**

* let fn = (a,b,c) => (a + b + c)

* let onceFn = once(fn)

*

* onceFn(1,2,3); // 6

* onceFn(2,3,6); // returns undefined without calling fn

*/

let fn = (a,b,c) => (a + b + c)

let onceFn = once(fn)

console.log(onceFn(1,2,3)) // 6

console.log(onceFn(2,3,6)) // returns undefined without calling fn

console.log(onceFn(2,3,6)) // returns undefined without calling fn