small refactor

[tormich]

• build coords list in one go
• same for heights
• tuple assignment makes possible to switch colorA and colorB in one line
• if __main__ is a standard python concept. I am putting it here to make Python gods happy

P.S.
Thank you for you videos. And math stendup is awesome! As well as the book!
I'm a big fan of yours 😄

[EhsanKia]

There's a lot of complicated code for fixing the coordinate loading, here's a 3 liner that achieves the same:

import json
with open(coordfilename, 'r') as fin:
    coords = list(map(json.loads, fin.readlines()))