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import { ListNode } from "../reverse-linked-list/ListNode.ts";
export default function deleteDuplicates(    head: ListNode | null,): ListNode | null {    if (!head) return head;
    const result = new ListNode(head.val);    let current = result;    while (head) {        if (head.val !== current.val) {            current.next = new ListNode(head.val);            current = current.next;        }
        head = head.next;    }
    return result;}