Too many too enumerate. Once had used an HTML lib that didn't properly escape characters. I was able to see the source, propose a change, and do it the correct

Too many too enumerate. Once had used an HTML lib that didn't properly escape characters. I was able to see the source, propose a change, and do it the correct way in my code. I won't say which one it was, but it was extremely popular. Used a JavaScript lib to create sheet music. The lib worked fine for the most part, but I needed certain features to work, and that required diving into the raw source and making many manual changes. If it was closed source, I'd have to figure out how to write the whole thing myself. That probably wouldn't have been possible for me. A popular API had an official Python implementation. It was "ready" for Python3, but there were a lot of bugs that would cause crashes. I was able to fix them and send back proposed changes. It took over a year for them to finally do the updates. I needed it that day.