class Nodeimport { Node } from "https://deno.land/x/masx200_leetcode_test@7.6.1/flatten-a-multilevel-doubly-linked-list/Node.ts"; ConstructorsnewNode(val?: number,prev?: Node,next?: Node,child?: Node,)Propertieschild: Node | nullnext: Node | nullprev: Node | nullval: number