var TEST = function () {

    function _handleExist(l1, l2) {
        let sum = NaN;
		let isAdd = false;
		let someOneIsNull = false;
        while (true) {
			
			sum = isAdd ? 1 : 0;
            sum += l1 ? l1.val : 0;
			sum += l2 ? l2.val : 0;
			
			isAdd = sum >= 10;
			if (isAdd) {
				sum-=10;
			}
			
			if (l1) {
				l1.val = sum;
				if (someOneIsNull && !l1.next) {
					l1.next = isAdd ? new ListNode(1) : null;
					return 1;
				}
				l1 = l1.next;
				someOneIsNull = someOneIsNull || !l1;
			}
			if (l2) {
				l2.val = sum;
				if (someOneIsNull && !l2.next) {
					l2.next = isAdd ? new ListNode(1) : null;
					return 2;
				}
				l2 = l2.next;
				someOneIsNull = someOneIsNull || !l2;
			}
        }
    }
    
    return {
        exec: function (l1, l2) {
            return (_handleExist(l1, l2) === 1) ? l1 : l2;
        }
    };
}();