lesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregateslesson 5 of 6 · groupby, joins, and first featuresgroupby, joins, and first aggregates
Write per_user(rows): group (user, amount) events and return a dict mapping each user to a (count, total) tuple — your first feature table. Print maya's features.