code: def find_pingback_urls(self, urls):
          
          pingback_urls = {}
  
          for url in urls:
              try:
                  page = urlopen(url)
                  headers = page.info()
  
                  server_url = headers.get('X-Pingback')
  
                  if not server_url:
                      content_type = headers.get('Content-Type', '').split(
                          ';')[0].strip().lower()
                      if content_type in ['text/html', 'application/xhtml+xml']:
                          server_url = self.find_pingback_href(
                              page.read(5 * 1024))
  
                  if server_url:
                      server_url_splitted = urlsplit(server_url)
                      if not server_url_splitted.netloc:
                          url_splitted = urlsplit(url)
                          server_url = '%s://%s%s' % (url_splitted.scheme,
                                                      url_splitted.netloc,
                                                      server_url)
                      pingback_urls[url] = server_url
              except IOError:
                  pass
          return pingback_urls
docs: Find the pingback URL for each URLs.