result = mCommandListeners.remove(listener);
HashSet clone = (HashSet)mCommandListeners.clone(); result = clone.remove(listener); mCommandListeners = clone;
	public boolean removeCommandListener(CommandListener listener)	{		if (null == listener)	throw new IllegalArgumentException("listener can't be null.");        boolean result = false;				synchronized (mCommandListenersMonitor)		{			result = mCommandListeners.remove(listener);		}				assert false == mCommandListeners.contains(listener);				return result;	}