Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

rollback

Discarding every change made in the current transaction.

conn.rollback() (SQL ROLLBACK) undoes all of the transaction's changes, returning the data to its state at the transaction's start; committed work is unaffected.