Thanks.
I realize that flat lines are not supposed to produce a signal. Perhaps I should not have used the word "flat" in my description. Since what I really mean is a series which rises, stays at the same level for 2 bars, then falls. A casual observer would look at the local minimum shown in peak_bug_real_GBPJPY.png and say, "that's a peak." peak() misses it.

Likewise in the chart above Red and Blue have trades places and have clearly "crossed over" yet crossOver is unaware.

Thanks for pointing out algorithms in the manual. Silly me.