text: // problem https://leetcode.com/problems/remove-duplicates-from-sorted-list/
  
  /**
   * Definition for singly-linked list.
   * function ListNode(val) {
   *     this.val = val;
   *     this.next = null;
   * }
   */
  /**
   * @param {ListNode} head
   * @return {ListNode}
   */
  const deleteDuplicates = function (head) {
    let node = head
  
    while (node && node.next) {
      if (node.val === node.next.val) {
        node.next = node.next.next
      } else {
        node = node.next
      }
    }
  
    return head
  };
  