docs: def hostname_for_event(self, clean_server_name):
          """Return a reasonable hostname for a replset membership event to mention."""
          uri = urlsplit(clean_server_name)
          if '@' in uri.netloc:
              hostname = uri.netloc.split('@')[1].split(':')[0]
          else:
              hostname = uri.netloc.split(':')[0]
          if hostname == 'localhost':
              hostname = self.hostname
          return hostname