I have a file that I use as a standard library. It’s mostly common data structures (like dynamic arrays and hashmaps) with functions I like and use often, which helps keep my code readable. I spent all week improving it. git reports about 2K lines added and 1.5K lines removed. I suspect most of the added lines were test code, and I managed to remove 100+ lines of code while keeping the behaviour the same. All the code in that file is run often, so if a bug exists, it'll likely be triggered. I increased coverage tests for that file, from ~80 to ~90. While I technically didn't make any progress this week, it’ll be less likely that I run into bugs, at least for that file.