-/*
- * Conventional binary search loop looks like this:
- *
- * do {
- * int mi = (lo + hi) / 2;
- * int cmp = "entry pointed at by mi" minus "target";
- * if (!cmp)
- * return (mi is the wanted one)
- * if (cmp > 0)
- * hi = mi; "mi is larger than target"
- * else
- * lo = mi+1; "mi is smaller than target"
- * } while (lo < hi);
- *
- * The invariants are:
- *
- * - When entering the loop, lo points at a slot that is never
- * above the target (it could be at the target), hi points at a
- * slot that is guaranteed to be above the target (it can never
- * be at the target).
- *
- * - We find a point 'mi' between lo and hi (mi could be the same
- * as lo, but never can be the same as hi), and check if it hits
- * the target. There are three cases:
- *
- * - if it is a hit, we are happy.
- *
- * - if it is strictly higher than the target, we update hi with
- * it.
- *
- * - if it is strictly lower than the target, we update lo to be
- * one slot after it, because we allow lo to be at the target.
- *
- * When choosing 'mi', we do not have to take the "middle" but
- * anywhere in between lo and hi, as long as lo <= mi < hi is
- * satisfied. When we somehow know that the distance between the
- * target and lo is much shorter than the target and hi, we could
- * pick mi that is much closer to lo than the midway.
- */