I'm here to make a serious case for using O(z) for asymptotic runtime complexity notation instead of O(n). After all:
The programmers of tomorrow are the wizards of the future. You're going to look like you have magic powers compared to everybody else. - Gabe Newell
It's not a huge change. In fact, it's just a simple swap operation. Also consider:
Any sufficiently advanced technology is indistinguishable from magic - Arthur C. Clarke
That's that.