docs: def do_callback(self, pkt):
          """Add the callback to the event loop, we use call soon because we just
          want it to be called at some point, but don't care when particularly.
          """
          callback, parser = self.get_callback_parser(pkt)
  
          if asyncio.iscoroutinefunction(callback):
              self.loop.call_soon_threadsafe(self._do_async_callback,
                                             callback, parser)
          else:
              self.loop.call_soon(callback, parser)