Some algorithm'll spot the samples.
The idea was sort of musical trolling. Initially I just wanted to loop those opening Led Zep bits and never start the song. UNFULFILLED EARWORM. As it turns out Magic Bus is near the same BPM and it makes my ears perk up like a busy little terrier in about the same way. Same with Fopp. So I figured I might try to make something out of beginnings only.
The result is that I pretty much trolled myself and needed something that sounded final. Thus the 99 Problems bit.