// Your code here.

arrayToList = arr => {
  	doStuff = (arr, obj) => {
    	if(arr.length){
          	console.log('arr ',arr)
        	obj.value = arr[0];
          	obj.rest = {};
          	arr.shift();
            return (doStuff(arr, obj.rest));
        }else{
          	console.log('else ', obj);
          	obj.rest = {value : arr[0], rest : null}
        	return obj;
        }
    }
    obj = {};
  	doStuff(arr, obj);
    return obj;
}

console.log(arrayToList([10, 20]));
// → {value: 10, rest: {value: 20, rest: null}}
//console.log(listToArray(arrayToList([10, 20, 30])));
// → [10, 20, 30]
//console.log(prepend(10, prepend(20, null)));
// → {value: 10, rest: {value: 20, rest: null}}
//console.log(nth(arrayToList([10, 20, 30]), 1));
// → 20