Occupied ports and notifications

I did:

bin/middleman server

The documentation then says:

Then visit http://localhost:4567.

However nothing happened there. This may be because I have had a sinatra app
running on that port.

Would it be possible for TryRuby to first check for open ports;
then use an open port; and also on the commandline show
which local URL I could use? Sinatra does that by the way.

Edit: Actually it now works at:

http://127.0.0.1:4567/

Perhaps the documentation can mention that we should wait a bit?
It seems it took a few seconds or so. Now it works hmmm.

bin/middleman server コマンドと、http://localhost:4567 について説明しているドキュメントから始めてください。コマンドが使用中のポートと起動タイミングをどのように処理するかを確認してください。利用可能なローカル URL を選択または報告し、ドキュメントでいつどこに接続するかを説明できれば完了です。