Last night I was catching up with the new season of the BBC series Endeavor, about the young brilliant detective Morse, recently demoted to beat cop.
One of his cop colleagues chided him that sometimes you need to apply shoe leather to a case, when brilliant deduction won't work.
This is a case where shoe leather is needed, looking for the blue math block < 5.
If you can code it, you can read it.
Here is the first example I found, in Screen1 of a prior load.
It's time for you to use your shoe leather.