code: func (w *ComparedValue) Close() error {
  	w.lock.Lock()
  	defer w.lock.Unlock()
  
  	// Set closed to true always
  	w.closed = true
  
  	// For all waiters, complete with ErrClosed
  	for k, val := range w.waiters {
  		val.SetValue(ErrClosed)
  		delete(w.waiters, k)
  	}
  
  	return nil
  }
docs: // Close closes the value. This can never fail. For a definition of
  // "close" see the ErrClosed docs.