Watch Python run your code one line at a time: names, objects, frames and output, drawn the way the interpreter sees them. Built from my Python_Fundamentals practice repo, with bugs and gaps fixed along the way.
Step through the walkthrough, then answer the "predict the output" cards before revealing. Say why, not just what.
Snippets live in snippets/<page>.json. Run python3 tools/pytrace.py python-fundamentals/snippets/<page>.json from the repo root to rebuild traces/<page>.js. Topics 2–20 are generated from tools/pypages/specs/<page>.py by tools/pypages/build.py, which also checks every puzzle and quiz answer against a real run.
Practice code: PritamDe166/Python_Fundamentals. Tags show which files each topic draws on; "gap" topics weren't in the repo; Part 5 adds topics beyond it.