Thanks for the tips, I managed to do it in my script instead nodes = ['wss://steemd.minnowsupportproject.org','wss://rpc.buildteam.io/','wss://rpc.steemliberator.com']
steem = Steem(nodes, wif = [posting_key])
Hoping to make the changeover in the future and will check out your tutorial series!
It's funny how that exact move doesn't work for Steem-Python anymore :D