public IEnumerable<IFileInfo> GetFiles(GlobPattern pattern)
	    {
	        return _names.Where(n => pattern.IsMatch(n.Key)).Select(n => GetFileInfo(n.Key));
	    }
	    public IDisposable Subscribe(GlobPattern pattern, Action<FileChangeEventArgs> handler)
		{
			throw new NotImplementedException();
		}
		    public LookupDirectoryFileSystemSubscription(FileSystem parent, GlobPattern pattern, Action<FileChangeEventArgs> handler)
			{
				_parent = parent;
			    _pattern = pattern;
			    _handler = handler;
			}
	    public IEnumerable<IFileInfo> GetFiles(GlobPattern pattern)
	    {
	        return _fileInfo.Where(pattern.IsMatch).Select(GetFileInfo);
	    }
	    public IDisposable Subscribe(GlobPattern pattern, Action<FileChangeEventArgs> handler)
		{
			var subscription = new LookupDirectoryFileSystemSubscription(this, pattern, handler);

			_directorySubscriptions.Add(subscription);

			return subscription;
		}
 public IEnumerable<IFileInfo> GetFiles(GlobPattern pattern)
 {
     throw new NotImplementedException();
 }