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import { ListNode } from "../reverse-linked-list/ListNode.ts";
export default function detectCycle(head: ListNode | null): ListNode | null {    if (!head) return head;    const cache = new Set<ListNode>();
    while (head) {        if (cache.has(head)) {            return head;        } else {            cache.add(head);        }        head = head.next;    }    return null;}