"It was mostly designating a particular global list to carry the water of remembering the checking history, and updating the name of another global variable to emphasize its responsibility to hold reading values . . ." reminds me very much of a jingle for a toy when I was growing up (way B4 your thyme [BBC cooking show pun]). It went something like "Circle in a circle, ring around a ring, with the Spirograph you do your own thing . . ." The plastic, gear-lined rings that fit together to allow a pen to move in such a manner remind me of the blocks used here to manipulate code. The difference is one needn't be a bloomin' genius to play with a Spirograph.
Thank you for your genius and time spent putting it to code.