a really tough day When I got up this morning, it's raining outside and I didn't want to go to library today. But I've already made an appointment with my friend to study together. So I forced myself outside and started to read a book named "mostly harmless econometrics". Really a boring book to me. I thought there would be numerous experiments inside, but for the whole over 250pages, only talked about difference to differences... indeed boring. I should take the book about data analysis in python, that way I can stand this whole boring afternoon