New top story on Hacker News: What was the nicest codebase you've inherited without the original author(s)?

What was the nicest codebase you've inherited without the original author(s)?
5 by _randyr | 0 comments on Hacker News.
What made this particular codebase stand out above others? What did the original authors of the code do well? Documentation? Tests? Perhaps nothing about the code itself, but rather the surrounding environment?