code: def is_broken_link(url):
      
      try:
          request = urllib_request.Request(
              url, headers={'User-Agent': 'Mozilla/5.0'})
          urllib_request.urlopen(request).read()
          return False
      except urllib_request.URLError:
          return True
      except SocketError:
          return True
docs: Determine whether the link returns a 404 error.