code: def _lazy_listen(self):
          
          if all([
              self._loop,
              not self.running,
              self._subscriptions or (self._pending and not self._pending.empty()),
          ]):
              self._task = self._loop.create_task(self._listen())
docs: Ensures that the listener task only runs when actually needed.
          This function is a no-op if any of the preconditions is not met.
  
          Preconditions are:
          * The application is running (self._loop is set)
          * The task is not already running
          * There are subscriptions: either pending, or active