docs: def start(self) -> None:
          """
          Start monitoring the base unit.
          """
  
          self._shutdown = False
  
          # Start listening (if server) / Open connection (if client)
          if isinstance(self._protocol, Server):
              self.create_task(self._async_listen)
          elif isinstance(self._protocol, Client):
              self.create_task(self._async_open)
          else:
              raise NotImplementedError