code: def _root_content(self):
      body = r"""<!DOCTYPE html>
  <html lang="en">
  <head>
      <meta charset="UTF-8">
      <title>Backend Server</title>
  </head>
  <style>
  body {
      background-color: white;
      margin: 0;
      padding: 0;
      min-height: 100vh;
  }
  .banner {
      height: 65px;
      margin: 0;
      padding: 0;
      background-color: rgb(20, 100, 130);
      box-shadow: rgba(0, 0, 0, 0.1) 1px 2px 3px 0px;
  }
  .banner h2{
      color: white;
      margin-top: 0px;
      padding: 15px 0;
      text-align: center;
      font-family: Georgia, Times New Roman, Times, serif;
  }
  .app {
      background-color: rgb(245, 245, 250);
      min-height: 100vh;
      overflow: hidden;
  }
  .card-header{
      padding-top: 12px;
      padding-bottom: 12px;
      padding-left: 20px;
      padding-right: 20px;
      position: relative;
      line-height: 1;
      border-bottom: 1px solid #eaeff2;
      background-color: rgba(20, 100, 130, 0.78);
  }
  .card-body{
      padding-top: 30px;
      padding-bottom: 30px;
      position: relative;
      padding-left: 20px;
      padding-right: 20px;
  }
  .card-title{
      display: inline-block;
      margin: 0;
      color: #ffffff;
  }
  .card {
      border-radius: 3px;
      background-color: white;
      box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
      border: 1px solid #d1d6e6;
      margin: 30px 20px;
  }
  .link-container {
      text-align: center;
  }
  .link-container ul {
      display: inline-block;
      margin: 0px;
      padding: 0px;
  }
  .link-container li {
      display: block;
      padding: 15px;
  }
  .center {
      position: absolute;
      left: 50%;
      top: 50%;
      -webkit-transform: translate(-50%, -50%);
      transform: translate(-50%, -50%);
  }
  </style>
  <body>
  <div class="app">
      <div class="banner"><h2>Backend Server</h2></div>
      <div class="card">
          <div class="card-header">
              <div class="card-title"><div class="center">Active Links</div></div>
          </div>
          <div class="card-body">
              <div class="link-container">
                  <ul>
                      $list
                  </ul>
              </div>
          </div>
      </div>
  </div>
  </body>
  </html>
  """
      if not self.pool:
          items = "<li>No active links.</li>"
      else:
          items = "\n".join(
              [
                  r'<li><a href="{0}">{1}</a></li>'.format(
                      "/{0}/".format(key)
                      if self.base_url is None
                      else "/{0}/{1}/".format(self.base_url, key),
                      key,
                  )
                  for key in self.pool.keys()
              ]
          )
  
      content = Template(body).substitute(list=items)
      return content
  
imports: from IPython import display
  import re
  import requests
  import threading
  import os
  from .None import _udash
  from gevent.pywsgi import WSGIServer
  from flask import Flask
  import socket
  import random
  from string import Template
  import logging
label_desc: Use image node_id 5 for calling the DispatcherApp obj's underlying member method code with example usage: obj._root_content() and returns: content