Sorry, I'm dumb. But I completely don't understand how the "test data" dates at the start of the article make any sense without the accompanying comments. Would you mind clarifying please? If so, thanks!

Edit: It's probably not even clear why I'm confused. But I mean, how does anyone know if any of the dates is supposed to be a "start and end date" or just a "start date" or just an "end date" without the comments? I assume I'm missing something obvious here...