Why 7?
The last released line was `3.0.1`. Version 4 never shipped. So one answer is simple: `3 + 4 = 7`.
The sillier answer is that it also gestures toward `(4 + 2)++`, which gets you into Douglas Adams territory fast enough to feel correct.
The final answer is even less scientific: 7 is your favourite number. That is not how most versioning schemes are designed, but it is at least honest.