can anyone explain me the workign of this code
/**

• Definition for singly-linked list.

• struct ListNode {

• int val;

• ListNode *next;

• ListNode() : val(0), next(nullptr) {}

• ListNode(int x) : val(x), next(nullptr) {}

• ListNode(int x, ListNode *next) : val(x), next(next) {}

• };
  /
  class Solution {
  public:
  ListNode addTwoNumbers(ListNode* l1, ListNode* l2) {
  ListNode* n1 = l1;
  ListNode* n2 = l2;

   ListNode* ans=new ListNode((n1->val + n2->val)%10);
   ListNode* curr=ans;
   int carry = ((n1->val + n2->val) / 10);
       
   n1 = n1->next;
   n2 = n2->next;
   
   while(n1 != NULL || n2!= NULL)
   {
       
       int sum = carry;
       if(n1!=NULL)
           sum+=n1->val;
       if(n2!=NULL)
           sum+=n2->val;
       carry = sum/10;
       sum = sum%10;
  
       curr->next = new ListNode(sum);
       curr = curr->next;
    
       if(n1!=NULL)
           n1 = n1->next;
       if(n2!=NULL)
           n2 = n2->next;
   }
   
   if(carry>0)
   {
       curr->next = new ListNode(carry);
       curr = curr->next;
   }
   
   
   return ans;

  }
  };