Python-based Lisp interpreters modeled after the 1960 McCarthy paper.

I wrote this set of Python files to try to help programmers understand the original LISP paper, assuming zero mathematical or Lisp knowledge. The original paper is a mind-blowing piece of computer science history for many reasons - I'd recommend anyone to try and get their head around it.I found plenty of fantastic LISP implementations which stay close to the original paper. But they are all fully-functional, practical implementations. The original paper builds from deeper fundamentals which it would be possible to write code in, albeit very impractical.I implemented these earlier iterations, so programmers can follow the paper step-by-step in a more familiar language than 50s mathematical notation.I am no expert in Lisp or mathematics, and intentionally went into this with no knowledge of Lisp beyond the original paper. I did not write it in the most elegant way, but in the simplest way for me to understand. So please don't take this code as a definitive statement on the language.However, this code really helped me to understand the original paper better, and to begin using Lisp with a better grasp of the spirit of the language.I'd welcome any thoughts from those who have more experience with Lisp or comp sci history.