Checkpoint
One last thing before we move on. Same surface as a write step — but the lesson doesn't complete until this passes.
Assemble the two-rung ladder end to end: learn the majority class FROM TRAIN, score both it and the rule tickets>=4 on the same test set with one shared accuracy helper, print an aligned board line per rung (:<10 and :.0%), then print whether the rule beats the majority rung — the 'does a pattern exist beyond common sense?' verdict.