P.S.
This helped a lot!
I've seen photographs here of a ball python going straight up a cinderblock wall.
My greatest fear is that he fell down the old drystone well under the house.
Before new floors were put in, I went down the trapdoor on a rope into that horrible abyss to rescue a cottontail that had fallen in.
It's at least 10 feet deep and the sides are just field stone laid one upon the other.
I didn't know if he could climb it or not but surely it'd be easier to climb than a flat cinderblock wall!
Because the new flooring is tongue and groove sheeting, there's no way [short of a chainsaw] that I can even look down there, now.