Ha! Two fools, one thought :-)
It's a nice idea but as Vladimir mentioned expand(), reallocate(), free() - all need now to worry about checking two singular values instead of one.
Since there's a long-established tradition that reallocate() and free() accept a null pointer, we can't (and probably shouldn't) change that. So I'm thinking in a way null as a singular value comes for "free".
Andrei
