How it's done?

Question

https://code.sololearn.com/cyZLarnaFw6N/?ref=app

Answer 1

The program author has stated inside his program as a comment, that the chat is simulated by predefined sentences.

So while it looks like real chat, it is not. He is just echoing or printing out his predefined variables which are the strings/sentences.

Answer 2

Хз