There was a bug in an embedded system I worked on that several engineers, software as well as hardware, spent months troubleshooting.

I eventually got called in and fixed it with a while loop and one function call inside of that loop. 4 lines in total, counting the brackets.

A very trivial change if you didn’t know why it was there, what impact it had on the system or how much it would have continued to cost in engineering hours if I hadn’t figured out what went wrong, why it went wrong and how to fix it.

I’ve spent a good chunk of my 15 years as a software developer as a pure “bug killer” and then you don’t really get to write that many lines of code, but the impact per line is big.