I was responding to a Drupal issue this morning, that involved using a = or a >= when I flashed back to my college professor teaching about guarded loops.  A quick google, and I found reference to his 1981 book, "The Science of Programming" whose synopsis says "This is the very first book to discuss the theory and principles of
computer programming on the basis of the idea that a proof of
correctness and a program should be developed hand in hand."  Why do I write about this?
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