I was curious how to implement DES one weekend so I decided to try it in
Python.

This program was written by reading 'DES Algorithm Illustrated' over and over
and over. It was written by J. Orlin Grabbe and it located at http://orlingrabbe.com/des.htm

I did not intend to add error checking or optimizing anything... that was
beside the point. Don't judge me. :P