He's unit-testing Germanium.resistivity(intensity, temperature) like so:

    fixed_i = lambda t: Germanium.resistivity(42, t)
    for t in range(100, 350, step=10):
        assertEqual(fixed_I(t), k*math.expr(t/tref))

Unfortunately fixed_i returns results akin to /dev/urandom because of broken hardware.

That is an absolutely fantastic summary. I upvoted the parent just to get this one more attention :D

Good questions deserve an upvote just as much as getting answered :)

If only high-school Chemistry was this easy, I would go back and do it again, just to be fascinated by nature.

Awesome explanation! Thanks.