Call, raise, or foldr

Yesterday I spent from 6:00pm until 3:00am in the Linux cluster working on the second half of 212 which is due at midnight. Don't worry, I'm done. There was a group of three people in the Linux cluster during that period. I just went in there to grab a pencil that I left there (it is currently 2:00pm), and those three people were there, in the exact same place. I am trying to convince myself that they went home and slept, and that they are not on hour 20 of a marathon programming crunch.