code: func (w *Watcher) Close(txn storage.Transaction) {
  	w.l.Lock()
  	defer w.l.Unlock()
  
  	if !w.closed {
  		w.close(txn, false)
  	}
  }
docs: // Close ends the watches on all queries this Watcher has.
  //
  // Further attempts to register or end watches will result in an error after Close() is
  // called.