text: const { Node, link } = require('./01-node');
  let first = link;
  
  function deleteNodeAtHead(link) {
    link.value = null;
    return link.next;
  }
  
  first = deleteNodeAtHead(first);
  console.log(JSON.stringify(first, null, 2));
  // {
  //   "value": "2",
  //   "next": {
  //     "value": "3",
  //     "next": null
  //   }
  // }