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export default function getKthFromEnd(    head: ListNode | null,    k: number,): ListNode | null {    if (!head) return head;    if (!head.next) return head;    if (k === 0) return null;
    let fast: ListNode | null = head;    for (let i = k; i > 0; i--) {        if (fast) {            fast = fast.next;        }    }    if (!fast) return head;    let slow: ListNode | null = head;    while (fast && slow) {        fast = fast.next;        slow = slow.next;    }    return slow;}import { ListNode } from "../reverse-linked-list/ListNode.ts";