No module named 'tkinter'

So, I recently had to reinstall Linux and hit the same "no module named 'tkinter'" error when first using TensorFlow that I had previously encountered and fixed. It is a particularly irritating error because, on a base install of Ubuntu 18 Desktop, simply trying "pip3 install tkinter" results in "no matching distribution found for tkinter".

The solution turns out to be the rather unintuitive "sudo apt-get install python3-tk". Enjoy!