Can someone explains me what does while loop do in this piece of code? I mean oroperator is used but what is the condition fror operator ? LINKEDLIST

````
// this is a code
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        int carry = 0, first, second;
        ListNode *head = new ListNode(0), *tail = head;
        **while (l1 || l2 || carry)** {
            if (l1) {
                first = l1->val;
                l1 = l1->next;
            }
            else
                first = 0;
            
            if (l2) {
                second = l2->val;
                l2 = l2->next;
            }

> Blockquote

````