   for (let k = 0; k < n; k++) {
        heap.insert(newNode(k, k));
      }
      report += checkHeap(heap);
      report += "\n";

      for (let k = 0; k < n; k++) {
        heap.insert(newNode(-5 * k, null));
      }
      report += checkHeap(heap);
      report += "\n";

      for (let k = 0; k < n; k++) {
        heap.insert(newNode(Math.random() * 100, 12));
      }
      report += checkHeap(heap);
      report += "\n";
      document.getElementById("report").innerHTML = "<pre>" + report + "</pre>";
