code: def _run_io_threads(self, handler):
          
          reader = ReadingThread(self.settings, handler, daemon = self.daemon,
                                                  exc_queue = self.exc_queue)
          writter = WrittingThread(self.settings, handler, daemon = self.daemon,
                                                  exc_queue = self.exc_queue)
          self.io_threads += [reader, writter]
          reader.start()
          writter.start()
docs: Start threads for an IOHandler.