docs: def connection_lost(self, exc):
          """Called when asyncio.Protocol loses the network connection."""
          if exc is None:
              self.log.warning('eof from receiver?')
          else:
              self.log.warning('Lost connection to receiver: %s', exc)
  
          self.transport = None
  
          if self._connection_lost_callback:
              self._loop.call_soon(self._connection_lost_callback)