text: 'use strict';
  
  const LinkedList=require('../linked-list/linked-list.js');
  
  function zipLists( ll1,ll2 ){
  
    let zipLists = new LinkedList () ;
  
    let linkedList1 = ll1.head ;
    let linkedList12 = ll2.head;
  
    if ( linkedList1===null && linkedList12===null ){
      throw new Error( 'there is no linked list entered here' );
    }
    else{
  
      while( linkedList1 || linkedList12 ){
        if (linkedList1){
  
          zipLists.append( linkedList1.value );
  
          linkedList1 = linkedList1.next ;
        }
        if(linkedList12){
  
          zipLists.append( linkedList12.value );
          linkedList12 = linkedList12.next ;
        }
      }
  
      return zipLists.toString ();
    }
  }
  module.exports = zipLists ;
  
  
  
  