docs: def __last_error(namespace, args):
      """Data to send to do a lastError.
      """
      cmd = SON([("getlasterror", 1)])
      cmd.update(args)
      splitns = namespace.split('.', 1)
      return query(0, splitns[0] + '.$cmd', 0, -1, cmd,
                   None, DEFAULT_CODEC_OPTIONS)