code: def make_list_threads_message(self, py_db, seq):
          
          try:
              threads = get_non_pydevd_threads()
              cmd_text = ["<xml>"]
              append = cmd_text.append
              for thread in threads:
                  if is_thread_alive(thread):
                      append(self._thread_to_xml(thread))
              append("</xml>")
              return NetCommand(CMD_RETURN, seq, ''.join(cmd_text))
          except:
              return self.make_error_message(seq, get_exception_traceback_str())
docs: returns thread listing as XML