Back in college I was writing a parser for a personal project in python. I was adding nodes to a set, but somewhere down the pipeline, some of the items I added to this set mysteriously disappeared!

I never removed anything from this set, nor did I replace it, so it baffled me that I couldn't find some items in the set.

It turned out the problem was I updated fields in these nodes that were used for taking the node's __hash__, which would prevent them from being found in the set

:|

Didn't happen to me, but to a friend. It was freshman year of college and we were taking an intro engineering course where we had to take apart an old camera and replace some gear in the camera with one we designed ourselves to change the shutter speed. We were split into groups of 3 and had to submit our first lab report detailing our design plan by week 2 into the quarter. Right before the due date, one of the kids in my friends group DROPS OUT OF COLLEGE because he thought the project (2 weeks in) was too hard, leaving my friend and her partner to finish his third of the report that he didn't do. They didn't even get a third partner for the remainder or the class. Two people had to bear the work of a quarters worth of assignments meant for groups of 3. Thankfully they were able to do everything and got a passing grade in the end.

"The best property a software engineer can have is their ability to work with others."