I did change the test_numberwords.py since the words for the tens
place didn't actually match the number, e.g. 43 was originally
written as "fifty-three" there. It was interesting to see the test
cases. I tried to test some of my own numbers as I was writing, but
I missed the case of numbers ending in zero. 60 becomes
"sixty-zero", which matches what test_numberwords.py was looking for,
but in real life people would be puzzled by the extra "-zero." This
higlights for me an important point about making sure cases to be
tested cover all the sort of edge cases.