Reminds me of the story of a farmer asking if an engineer can help him identify sick ostriches on his farm. So to identify a sick ostrich, it doesn't eat anymore, so the engineer develops a tilt sensor that you strap to the ostriche's neck, and if it doesn't tilt enough times a day the ostrich didn't eat and a LED would light up red indicating the ostrich is sick and requires the farmers attention.

Now the problem is to separate the sick ostriches from the healthy ones. So the thinking is you connect the ostrich camp with a narrow passage to another camp, and put out food in the other camp and as the ostriches move to the new camp you capture and divert the sick ones.

Turns out that when you put out food in the new camp, only the healthy ostriches will move to the new camp and the sick ones will stay behind because they are in any case not interested in food.... which negates the need for engineer and his sensor in the first place :D