yesterday I somehow only red "can't...", and not "CTRL + C can't..."...

Yesterday it said that. I edited it after replying to you earlier.

I think I might drop a follow to this guy: he has a lot of undervalued content I have to check!

He's got the best flask guide. Not in videos, but on his homepage.
When I first found it, I didn't really get it, because it's more targeted at people, who already tried doing the same things in other languages/libs or by themselves.