Some write only comments, not code
Years ago I had to port a rather large body of C++ code, with which I was completely unfamiliar, to Linux. At some point I came across a header file that was #included all over the place but contained nothing but a comment. It said, roughly,
// Since AIX has WIN32 API emulation now we can throw away
// the whole UNIX branch.
Biting the hand that feeds IT
